Guide to Aggro

=Guide to Aggro=

Aggro, short for aggression, in it's simple form, is how AI controlled entities (heroes, enemies, etc) select what targets to kill. Knowing all the fine print can enable you to manipulate that behavior to your favor. To that end, this article start with the basics of aggro, then moves more into how it can be manipulated to your favor.

Terms Used
Several terms are used here, which for clarity should be defined first:


 * Aggro Bubble. This is the small circle that is displayed on your minimap. Every enemy has a similar aggro bubble of its own.  It is important that your awareness not extend only to your own bubble, but to your foes, and any ally that may enter your foes bubble.


 * Aggro Radius. This refers to how far you need to travel before a foe will stop chasing and give up.  For stationary patrols the radius is centered at the spot the patrol initially stood at.  For moving patrols, the radius is centered at the spot the patrol leader was standing at when aggro was initiated.


 * Melee foe. This is used in this document to refer to foes which use melee attacks.  They may still use spells, as in the case of Smite Crawlers which are monks.  What matters is that the base attack is not ranged.


 * Caster foe. This is used in this document to refer to foes which use ranged attacks.  Rangers and Paragons are included in this group, although they are not true casters, their aggro follows the same patterns as elementalists and mesmers using staves or wands.  These foes can use touch skills, as in the case of Skeleton Wizards which use Shock.  What matters here is that the base attack is ranged.

States of Aggro

 * No aggro
 * Active Aggro
 * Breaking Aggro
 * Fleeing Aggro

No aggro : Put simply this is when foes haven't seen you yet. Typically this is because you haven't entered their aggro bubble, but other factors can affect this. For example, some foes are incapable of seeing you at any range until you attack them, and others may see you from an extended distance and come towards you to attack you. Without aggro, if a foe dies, you do not gain experience points, and the foe leaves no drops. You do however receive a morale boost if a boss was killed.

Active aggro : The monster has seen you and your party and will initiate attacks against you.

Breaking aggro : For whatever reason the foe has given up on killing you, and heads back to where he came from.

Fleeing aggro : Enemies will run away from area of effect spells after being in them for some time, or when taking a lot of damage in a short time period.

Target Selection in General Melee
Given a range of targets, there are a number of criteria that dictate which target a foe will pick. These factors include :


 * Health
 * Armor
 * Health Regeneration/Degeneration
 * Movement Speed
 * Distance from the particular foe
 * Self defense

In general, they work out to a factor of time -- How long will it take for the foe to kill you. The less time he needs to kill you, the more likely it is to try and do just that.

Health : The lower your health, the fewer hits it takes a foe to kill you. Thus, your foes will favor anyone with low health. Conversely, more health means you are less likely to be targeted.

Armor: How tough are you? The stronger your armor, the more work is involved in killing you.

Health regeneration/degeneration : High health regeneration will reduce your chances of being the monsters target, while the opposite is true for degeneration.

Movement Speed: Both yours and your foes. Can your foes catch up to you quickly? If not, you may be ignored in favor of an ally that is less able to flee.

Distance: This goes hand in hand with snares. If the foe moves very slowly, it will favor greatly any targets that are nearby.

Self defense: A foe may choose to switch from their current target to someone who is attacking them.

Acquiring/Losing Aggro
There are several ways to acquire aggro:
 * Enter the foe's aggro bubble. This works on most foes, however in some low level areas foes are oblivious to this particular rule.
 * Get near a foe's aggro bubble. Some foes (eg: Kournan Spotter) are aware of you at an extended range. Typically, this isn't an extended aggro bubble as if you had actually aggroed the foe, his party would charge you too.
 * Land an attack on a foe -- This works, if your attack lands.
 * Target the foe with a spell -- This triggers aggro when the spell successfully completes. The fact that aggro waits for the spell to finish can be exploited to the purpose of targeting the foes with powerful long casting spells such as Meteor Shower.
 * Aggro a party member of the foe.
 * Acquire aggro through an ally -- If you target an ally with a skill, you will aggro any foes that ally has aggroed. This can be used as a simple exploit for earning experience when you aren't participating in the fight, of use if you have to work off death penalty.  Note that skills operating without a target, such as Heal Party do not acquire aggro this way.

Losing aggro is a rather simple proposition:
 * Die. While this is a very simple way to lose aggro, this has a very significant implication for farmers: Aggro is required for drops. This means that if everyone with aggro dies, and then the foe dies, no drops are made.  Having a live but unaggroed party member inside radar range of the dying foe will not change this.
 * Flee. If you move outside the aggro radius of a group of foes, they will stop chasing you. Alternatively, if you have a sufficient combination of distance and speed, you can lose aggro.
 * Sacrifice. Sometimes simply running isn't enough.  If your foe is faster than you, something more than just running may be needed.  When a foe kills something, it needs to select a new target.  If no targets are available, aggro is discontinued.  Typically, you only need to be outside aggro radius of the foe when this happens.  Often, the sacrifice is a team-mate, but an untamed animal, or a second group of foes hostile to the perusing group can also work.

When aggro is lost, a couple things happen. In the event of a loss of aggro through fleeing, the foes will run back towards the initial point of aggro a distance, then return the remainder of the distance at normal patrol speed. Only when the foes resume movement at patrol speed is aggro reset. Until then, if you are inside their aggro radius and meet their criteria for a target, they will resume the attack. In the event of a loss of aggro through a death, aggro is immediately reset and foes return to the point of aggro at normal patrol speed.

Solo Expeditions
It's you versus the world. Or well, every foe in the area you care to try killing. What possible tricks can you employ to make aggro go your way? First, you may notice you have two general types of foes, and they handle aggro differently:
 * Melee foes -- These are your axe warriors, your hammer warriors, your shambling horrors, and such. Anything that needs to get into touch range to cause you harm.
 * Ranged foes -- Anything that doesn't need to touch you to hurt you. This includes rangers, spellcasters, and the odd spear chucking paragon.

Against Melee
Going up against your non-ranged attackers presents several advantages, and drawbacks. For advantages, things will run right up to you so you can use AoE skills to kill them en-masse. For drawbacks, these are more prone to flee if you start hurting them, and they are more prone to block your movement. You have to be careful to not stand still during initial aggro with a group of melee attackers, or they may restrict your movement. If you are going to kill them in place, that's fine, but if you want to gather several groups together, this becomes a hindrance. Because these foes are more prone to flee, you may find that you need to either snare them to hold them in place, or use techniques to keep them from getting away. One technique is to block their flight path, make it such that when the foe tries to run directly away, it is running into a wall. Another technique is to snare him. You can use spells, but in a solo build a snare is a precious skill slot better used for buffing your damage, or simply staying alive. Not to worry, there is the low-tech snare: The wand snare. This doesn't have to be a wand, it can be a staff, spear, or even a bow. The argument can be made strongly for a spear: This lets you carry an enchant mod on the spear (required for many solo builds), but throw a mastery mod on an offhand, a combination not possible with a staff or wand. So long as you are actively striking a foe, it won't flee. While swords and axes could be used for this, if you want to pull back a foe that has already fled, but are yourself boxed in and unable to chase, a sword or axe won't suffice. You want something with range for your attack snare, and a wand or spear is perfect.

An interesting mechanic becomes apparent in the melee solo combat: three foes will always remain to attack you. If you have four foes attacking you, at most one will flee. If you have 50 foes attacking you, at most 47 will flee.

Against Ranged
Your foe has range to attack you with, so it won't clump with all its allies nicely on top of you, and if you try to bring the fight right to it, it may back off. This can render melee and AoE attacks of limited utility against some casters in a 1 vs many scenario. This can be dealt with in a couple of ways. You can find a bottle-neck to clump the foes together in, or in some instances you can drag them against a wall -- Since they often spread out in a specific pattern around their target, the wall can be used to force your foes to pile up in one spot. As far as they care, it is as near as possible to their desired positions, but for your own purpose this can place them in one spot for easy nuking.

Sometimes foes behave according to a kind of designate role.

The designated caster: The designated caster is rather harmless. He attacks you like any other foe would normally, wanding, casting spells, etc. He also doesn't flee if approached, making him a good target for melee attacks, and something that won't flee from a mob of melee that you are trailing. In short, he is your average foe doing what foes do best.

The designated kiter: This guy can be a pain. He'll run from you, it won't even bother to wand you, an unpleasant thing as some solo builds make use of Shield of Judgement, which only does damage to foes that bother attacking. The designated kiter may contribute spells, but otherwise all you can do is snare and kill him, or kill the designated caster. Once the designated caster is dead, the designated kiter changes role to that of the designated caster. The designated kiter isn't a Solo only phenomenon, it may also be encountered in the general melee that involves a full party. In that scenario you may be in a better position to snare it, but you may be more effective just to ignore the kiter while it is in this role.

The Hit and Run
As the name implies, this is a hit and run farming tactic. You hit the enemy once, and run away. Your goal with a single hit isn't to kill them in a single frantic fight, but to injure them gradually over time, while taking no damage yourself. A common build for this involves the use of Splinter Weapon, Barrage, and 3 fast recharge run skills. You run away the moment your attack is in the air. When the attack lands and aggro starts, aggro is lost immediately: You are moving faster than your foe, away from it. Left with no hope to catch you, it breaks aggro, and you are free to approach and continue.

Group Expeditions
When you have more than one party member, it's not a matter of getting aggro or keeping it. It's a matter of keeping aggro where you want it. Sometimes people go for the general melee, where your monkage and damage is sufficient to not require special treatment, but sometimes things hit a tad harder than your monks can keep up with in a general melee, and so has evolved the role of the tank.

The tank: Your tank need only survive all the attacks coming against him, however he still should to look appealing to your enemy. Whether that's low armor, low health, a self-snare, or no regen, your tank will be more appealing to the enemy with one or more of these in place. Another tactic is pulling, so that you can control the size and shape of your aggro, making it harder for your party to goof fatally, and easier for your tank to keep aggro.

A Sticky Tank
Your tank should (in most instances) be sticky to aggro. If a foe is given the choice of attacking your invulnerable tank or your squishy monk, it should feel that its time is better spent attacking your invulnerable tank. Low armor, low health, self-snares, etc... It ultimately doesn't matter how, just have something about your tank that is appealing to aggro. Using other tanking methods to control aggro can make this moot, but only if your tank is perfect, and your nukers are perfect, and your monk is perfect... In short, if anyone does something wrong at the wrong moment, aggro can have the option to slip around the tank and onto you. You will fare better if the foe decides to pass up this option when it is presented.

The Body Block
The body block works by the tank blocking foes with his body. He aggros a foe, and then stand up against some obstacle, blocking the path of that foe to the rest of your team. In its most often used and basic form that's all there is to it, your team mates come in and kill the foe, but if you want to quickly clear an area, there is more to follow.

In the initial pull, the melee foes will ball up on the tank. Any casters will stand back and attack from a distance. Ideally, you want all the foes in one spot, so that any AoE skill used on any foe hits all foes. To achieve this from this stage is simple, but it may help to understand why it works. All you do is send a monk up to heal the tank with a direct spell, as opposed to a party heal. That's it. By directly healing the tank, that monk aggroes everything that the tank also has aggroed. All those casters and rangers that are past the tank become aware of this new target. Your monk, likely squishier than your average tank, suddenly has the interest of the entire enemy force. Most will target the monk and come forward to kill him. You now have your monk back up out of casting range on the tank. All the ranged foes rush up to the tank and get stuck. Much like if you try pathing to something in town and get caught on an obstacle, the enemy has clicked on your monk and tried pathing to him, only to get stuck on the tank. Now that you have a small ball of foes, you turn your nukers loose.

About camp casting: Camp casting is where you stand in one spot and cast a series of spells. When using a tank to body-block, this practice is often discouraged expressly because of how it affects aggro. Ideally, your casters walk up to very edge casting range, cast a single spell, and back up. Yes, this slows down your damage, but it is is doubly important if any of the aggro is not properly blocked by the tank, or if any ranged attacks (spells, arrows, etc) from that ball of foes can threaten your casters. If you camp cast, you have just set yourself up for an unpleasant surprise. What happens with your first spell, whether you target the tank or the enemy, is you aggro each enemy attacking the tank and become the target for their next attack. You then stay around to cast a second spell, letting these enemies finish their current actions. Some will lob their next spell or attack at you directly, but if you back up after your first spell the enemies will find you out of range after they finish their current actions. Deprived of a fresh target these enemies will continue to attack the tank.

The Open Field Tank
The Open Field Tank tank gets its name from the ability to tank foes without the aid of walls or obstacles. Unlike the other tanking methods that can tank one group or six groups of foes with near equal ease, the open field tank can only aggro a single group at a time. He's not blocking the foes. What the Open Field Tank does is manipulate aggro so that the only target the foes have any interest in is him.

For Large Aggro
This works best with stationary groups. Moving patrols can work too, but when tanking for large aggro, the open field tank manipulates the Aggro Radius to your advantage, which is something that can change with a moving patrol.

Once you have aggroed foes, you run, leading them to the edge of the aggro radius. Once they break, you re-aggro them, and work to sort out where exactly the line is that crossing causes them to break aggro. You then place your tank just inside the aggro radius, and your casters outside it. With your casters outside the aggro radius, the enemy will ignore them. They have eyes only for the tank. All that remains is get the enemy in a ball and kill them.

A problem occurs here: The balling technique used for the traditional tank won't work here. That is because foes don't properly aggro on the casters in back, and you lack a choke-point in the open field to bring all the foes together. However, if during the initial pull, your tank zigzags, all the casters will ball up. If he then pulls the casters to one side, walks behind them, staying inside the aggro radius, and pulls them to the other side, he can get the enemy casters near the edge of their aggro radius, then walk up to (or just behind) them to bring the melee together with the casters. Some casters are given a stand-off spot, a spot to stand at a distance from the tank. Walls or obstacles can be used to get these foes to stand where you need them, but in a truly open field you need to kill them individually.

For Small Aggro
This is trivial compared to the large aggro open field tank, but only works with enemy groups of three or fewer.

Have your tank run up and gather them up. Then he needs to stand perfectly still. As long as the tank does not move, three foes or fewer will continue to target only him until they are dead. This only works with three and fewer, if there are four foes, one will change targets, if there are ten foes, seven will change targets. You may be able to keep a greater number of foes on the tank for the purpose of running past, but once foes are given a need to defend themselves, all but three will flee the tank for other targets.

Pulling
Sometimes you don't want to fight the enemy on his home turf. What you instead want to do is pull your enemies them to your home turf. It may be that you don't want patrols joining in your fight, or that you are worried about getting other nearby groups dragged into the fight, or perhaps you don't want to trigger a hidden group of foes that you suspect may be present.

There are some tips and tricks to doing pulls.

Basic Pulling
This typically starts by giving picking a spot to fight at, then giving someone a longbow or flatbow. These bows have the longest range of any weapon, and so are ideal for plucking a foe for 1 pt of damage. Having thus annoyed the enemy, your puller runs back to the party and a normal fight ensues. You may have the tank pull, so that he can arrange the aggro such that none of it leaks onto your party, our you may give the task to a ranger, who may be picked for the chore frequently and have experience in how to do a pull well. The most common way for a pull to go wrong is that he may strike a foe in one group that is standing too close to a foe in a second group, aggroing both groups. If this happens, many parties will just break aggro completely and retry the pull.

Long Distance Pull
Lets say that you are at one end of a zone, and have an enemy you want to fight. At the opposite end of the zone is the spot you want to kill it at. Lets say this is a modestly large zone too, like Snake Dance. Some people would think that foes won't pull that far. They'd be wrong, but there are aspects to it that make it difficult.

First, you need a target to pull. Something that can be distance pulled. Stationary groups won't long distance pull, their aggro radius is fixed. So you need a patrol, and not just any patrol, but one that patrols slower than you run, or you'll have problem catching up to them for each cycle of the pull. It'd be impossible to long distance pull a patrol that moves faster than you, difficult (at best) to pull a group that matches your speed, and relatively trivial to pull a patrol that normally walks. What you are going to do here is exploit the patrol aggro process.

When you aggro a patrol a singular thing of import happens, with respect to the long distance pull:
 * The patrol leader's current position is marked as the center of the patrol's aggro radius.
 * This doesn't happen for stationary patrols, only for moving patrols, which is why stationary patrols cannot be long-distance pulled.

It's important to understand the de-aggro process, or you may never get anywhere with your pulls:
 * 1) The patrol has determined that it cannot reach you before you leave the aggro radius.
 * 2) The patrol runs toward the center of the aggro radius for a distance.  (The distance varies based on how far it was pulled)  During this flight they may occasionally stop for a brief moment, but they resume flight almost immediately.
 * 3) The patrol stops and stands still a slightly longer moment than seen during normal flight. At the end of this stage, the aggro radius is reset.
 * 4) The patrol proceeds at patrol speed to where the patrol path was initially interrupted
 * 5) The patrol resumes the normal patrol pattern.

What you are going to do is come in at step 4 and re-aggro the enemy group, after the aggro radius has reset and before they get all the way back to their patrol path. This lets you pull them again, but to a new, more distant spot. If you pull a radar or further and to a spot where a return to their normal patrol is blocked by an obstacle, they can become unable to return to their patrol, and will instead stand stationary, staring at their obstacle. Used judiciously, you can cause them to become scattered this way, letting you pick a single isolated target to kill.

Now that we have the mechanics out of the way, lets describe the actual pull

You take out your trusty long bow, and tickle an enemy patrol. Next, you run away. If you can survive it, you will zig-zag back and forth, the end result being that you effectively move slower. This gives foes a chance to catch up after stopping to cast a spell or an attack, so they don't fall behind the rest of their allies, and you really don't want them falling behind, due to the singular element of aggroing a patrol mentioned above. Eventually, the enemy opts that you have run too far to interest it, so it breaks aggro and starts running away. You don't chase after them yet. Once the patrol pauses for about a half second, you chase in after them. They will start walking back after that pause, so be ready and get an arrow in the air as soon as you can. Wait for it to hit before you run away, and as before, if you can survive it, zig-zag again. You can then repeat this cycle until you are satisfied.

Why the heck would you want to pull a patrol across the map? What possible purpose could it serve?

Well, two:

First, it lets you get a particularly nasty group to a favorable spot for tanking. Sometimes, those big open areas just arn't equipped with walls for your tank to use to keep them in place, so being able to pull them to a handy wall helps.

Second, it lets people who want to death level (the act of letting foes level up by killing you multiple times) get numerous patrols to a res-shrine for leveling.

Aggro Gone Wrong
Up until now, we've discussed what happens when aggro goes well, but aggro doesn't always go well. Sometimes, for whatever reason, something goes wrong. If sufficiently out of round, you may need to have your party flee the aggro.

There are different ways aggro can go awry. You need to be alert for them and how to deal with them.

The Multiple Aggro
Whether it was pops underneath the patrol that you attacked, or more patrols that followed behind it, you've just bitten off more than you you were expecting. While good groups can handle a double or triple aggro with relative ease, the general rule of thumb is if your monks are unable to keep up, or if you are not killing things quickly, to break aggro and use a pull.

Being alert to patrol routes, and using pulls whenever pops are suspected are good ways to avoid multiple aggros.

Back Aggro
Back aggro occurs when, during a fight with one group of foes, another comes up from behind and starts killing your unprotected casters.

To avoid this, you need to watch patrol movements and pull whenever you are uncertain of what path a group will take or how far an individual might wander. That said, this still sometimes happens. When it does, if there is room past your tanks to fight without aggroing still more foes, you can have your casters run past your tanks and minions, essentially turning your formation around to attack in the opposite direction. With any luck, you've killed enough of the group you had started with to make them largely a non-issue in terms of choosing your casters for targets (see the Open Field Tank for Small Aggro above). Breaking aggro may not always be an option here, as the new group of foes often blocks your path of escape.

The Overzealous Ally
One of the more common forms aggro gone wrong, this is where your ally, in the heat of fighting the foes in front of him, charges forward far enough to aggro another group of foes. Minions and henchmen are popular for doing this, although allies such as dwarven ghosts or helpers for quests can also cause this to happen. With a sufficient force of minions and decent monks and damage, you may even be able to survive double, triple or even quad aggro from this, but unless you plan to kill the enemy groups enmasse this way, it is suggested you simply pull foes a full aggro bubble away from other aggro before letting allies/minions enter the fight.

The Extra Monk
This is the case of an extra monk from some nearby and uninvolved group doing what it does best: Healing the wounded. This is the monk that takes a few steps away from its own group to heal allies in the group that you are currently attacking.

Where this goes directly from bad to worse is when something aggros the extra monk. It doesn't take much. It doesn't take casting a spell on it or plucking at it with a bow. All it takes is something, be it your tank, your minions, or an over-zealous dwarf ghost to enter its aggro bubble. This is often very easy to do: A monk will get to to roughly aggro range of something to heal it, and if a tank or minion is attacking that same something, you stand a good chance of getting aggro. Once you aggro the extra monk, the party for that extra monk will now come over and join in the fight. Very likely, the group you were killing has a monk, and the new group also has a monk, making it somewhat difficult to kill anything. What you need to do when that extra monk starts walking over to heal is kill any monks in your current group of foes, and try your best not to aggro the extra monk. If you have minions, this is a lost cause, but if you have only tanks, your tanks can back away from the extra monk, or you can pull the entire group away from the extra monk. If you are feeling confident, you can continue fighting in place, and make plans to target the exposed monk once the fight winds down sufficiently.

If you do wind up with a double aggro and both enemy monks are still alive, your best option may simply be to break aggro and retry with a pull. With two monks that heal each other, killing anything becomes difficult, and your own party is taking twice the damage, taxing your own monks.

To preemptively prevent this problem, you can pull the first group away from any other nearby foes before attacking it.

The Leak
Your tank has everything balled up, and then a single foe steps around him to attack your monks. This foe is called a leak, and is handled by:
 * 1) Having a secondary tank.  Often, this is the prot monk as he is often well equipped to serve in this role, and often has under 400 HP, allowing the leak to stick to him firmly.
 * 2) Targeting the leak so that it can be killed first.

Unless you have a secondary tank that can handle the foe well, you need to kill the leak promptly. If that foe happens to be a nuker, it really doesn't matter how well your secondary tank can handle the leak, the leak still needs to die. These leaks can damage your back-line, and in Hard Mode, there may be times where your monks are not enough to protect against a single elementalist leak. Killing it before it kills your own casters is vital.

Having an experienced tank can limit how often this occurs, and letting him set aggro where he wants it before beginning a fight will help.

Avoiding camp casting can help reduce the chance of leaks, and if the leak does sufficient damage to your casters you may need to cut and run. As a general rule of courtesy, if the tank asks you to run, then run. He will want to get to a safe place he can die at to be ressurected later, and the longer you take to run the less likely the tank will accomplish this.

The Dead Monk
While strictly speaking this doesn't involve any manipulating aggro, it is an all to common reason for parties to fail when aggro goes wrong in even small ways.

Your monks keep your party alive. Typically groups run with 2 or 3 monks for healing and protting, if one or more die, your non-monks are going to have to res that dead monk. Yes, resurrection skills are classic monk skills, but when you have a dead monk, you are now short 33% or 50% of your healing capacity. Your surviving monkage is too busy keeping the rest of the party on its feet to bring up a dead member, and it will eventually fail without that dead monk helping. To avoid this, make sure at least 1 non-monk has a hard res to use whenever a monk or other party member dies. That leaves your remaining, over-worked monks the singular task of tending to the living until the resurrected monk has recovered enough energy to be effective again. If your dead monk isn't up promptly, it may be best for the party to just cut and run. One or two dead party members is a small thing. A party wipe is not.

Enemies Fleeing Aggro
Sometimes foes will run from you.

The Terrified Enemy. Your foes can flee in a solo tank scenario when too many melee foes take damage, but this can also happen if you are attacking past an obstacle (through a wall, down a cliff, etc) and the enemy is unable to attack back. What happens is it eventually comes to the conclusion that standing around for the slaughter is unwise, and it runs away. In fleeing, it will even avoid its normal patrol location. This flight can take them out of the range of your spells, requiring you to go around and confront them directly. Sometimes, due to a glitched spawn or other reason, you may not have the option of going around, and will need to break aggro fully before the foe will resume normal behavior. Sometimes having the person with the active aggro standing as close as possible to the obstacle will have the enemy come forward. As an alternative, you can try getting everyone off its radar completely, resetting aggro for the entire party. <!This loss of 'panic' aggro needs formal testing, I have not explored this in depth at this time>
 * Having the whole party leave the radar may be overkill, but with how aggro transfers at the mere cast of a spell, a monk healing someone from some environmental damage will pull aggro onto the monk. Other members using other skills can result in the whole party maintaining aggro, and giving it back to the party members who left the radar.

By working together to spike down individual targets, you may be able to avoid triggering this behavior in the first place, and by picking where to attack from, you can control where the foe flees to. Consume Corpse can also be used to chase after foes through the bodies of its fallen allies.

The Lost Patrolman. Another instance when foes will flee aggro is if members of a single moving patrol becomes widely separated. If you aggro a foe and the party leader of that foe is not in radar range, the foe will run towards its own party leader. Sometimes this isolated patrol member is stationary, sometimes it is on an active patrol. A lost patrolman can glitch such that it wanders into aggro of you, and being isolated from its leader it flees only to lose aggro and resume the patrol back towards you.

Epilogue
Whatever happens out there in the game world, remember that your opponent works by rules, and those rules are designed to make it possible to kill you as quickly and efficiently as possible. A true aggro artist will exploit these rules to his own advantage. It is hoped that this document gives you the tricks you need to do just that.

Best of luck in your hunting!