Guide to defeating doppelganger

The following tactics have been suggested to beat the Doppelganger:

General

 * The Doppelganger will have the same skills you equip, so don't equip any skill you wouldn't want used against you.
 * Exception: PvE skills are not copied (with the exception of PvE Rituals in Normal Mode only), so you can bring whatever you want from those. Ursan Blessing for instance is a good choice, and with high enough norn rank, can make the Hard Mode mission take less than fifteen seconds. With lower norn rank, it will be a tough battle, but will be decidely more easy than with regular skillsets. Pain Inverter also works very well.


 * Think very carefully before bringing any skill that can be used to heal yourself.


 * The AI generally prioritizes skills to the left of the skill bar.


 * Equip lots of slow-casting self-buffs: the less useful in the one-on-one fight, the better. The Doppelganger will waste time at the beginning of the fight casting every buff on itself.


 * Cast any self-buff enchantments before stepping on the third stone that starts the cut scene; they will last into the match. Cut scenes no longer run in real time, so any enchantments with a duration will not expire or run down their time during the cut scene.


 * Dodge arrows: Stand as far away from the Doppelganger as you can be and still cast spells on it, and strafe left and right as fast as you can. Make sure to constantly tap both ways. This twitchy movement will cause the Doppelganger to shoot wide and miss most of its shots.


 * Equipping skills like Frenzy (in Normal Mode only) and Healing Signet but not using them yourself gives you a great advantage.


 * Equip skills like Spiteful Spirit and Backfire, cast them on the Doppleganger but do not attack it, it will kill itself very quickly.

Hard Mode Notes


 * In Hard Mode, the Doppelganger will deal a lot more damage simply with its attacks. Taking skills to counter this is greatly advised.

Profession specific tips
If you have any problems defeating your doppelganger, look for profession specific tips below.

Elementalist

 * Bring lots of skills with very long cast times. The Doppelganger will usually waste its time casting these skills, giving you plenty of time to kill it. When using this strategy, consider using skills like Meteor Shower or Maelstrom.


 * Step out of AoE DoT spells like Meteor Shower or Maelstrom; the Doppelganger usually will not.


 * Do not equip skills that could disrupt your spell casting (like Gale or Earthquake).


 * Cast glyphs before stepping on the last stone. This will give you an advantage in battle, as you will waste less time casting.


 * Cast Kinetic Armor before entering and bring a cheap, spammable spell with which you can keep kinetic armor up. Bring one fairly limited interrupt (so you won't be interrupted very much), and use it when the Doppleganger when tries to cast kinetic armor, leaving you with an enormous armor advantage.


 * Take Iron Mist, it will generally use it on you, making you invincible as long as you don't bring any Air Magic spells.

Hard Mode Notes


 * Hindering its damage dealing ability may be of great help, as you do not have as high armor as other professions have. Blinding Flash or Blinding Surge is a good option to stop it from dealing too much damage with attacking.

Mesmer

 * Backfire is a very useful skill. Consider using it with other cheap, harmless spells. Just cast Backfire on it and let it cast itself to death. Be careful not to let Backfire trigger on you though. (Placing it at the end of the skillbar will usually make it cast last by the Doppleganger).


 * Anti-melee hexes like Empathy, Clumsiness and Spirit of Failure can greatly help in letting the Doppelganger kill itself. Consider combining this with Spirit Shackles and Mind Wrack. When using this technique, just do not attack it.


 * Having Illusion of Weakness on your bar and casting it before entering the Doppelganger's arena can provide you with great healing. Placing the skill on the right of the skill bar makes it less likley the Doppleganger will use it.


 * Shatter Enchantment is a good idea. Take some cheap enchantments and let the Doppelganger cast them on itself, only to shatter them.


 * Be careful with interrupts. The AI almost always has faster reflexes than you, so it is likely you will get interrupted.

Hard Mode Notes


 * Due to its AI, the Doppelganger will not use spells when at low health and hexed with Backfire.

Monk

 * The AI will not use Regeneration skills like Healing Breeze to counter health loss, but will use it only to counter degeneration. Use this to your advantage.


 * Monks have little options to deal damage, so try focusing on Smiting Prayers.


 * Bring Retribution and Holy Wrath to let the Doppelganger kill itself. As this will drain your energy completely, use Signets to heal yourself.


 * Using Restful Breeze as an alternative to Healing Breeze along with Retribution and 12 points in Healing and Smiting prayers will guarantee no healing for the Doppleganger. It will kill itself in under 2 minutes this way, just don't attack.


 * Get the Doppleganger to cast Life Attunement to dramatically reduce damage from its attacks.

Hard Mode Notes


 * In Hard Mode, the AI will force the Doppleganger to use Healing Breeze.


 * Use Retribution, Shield of Judgment, Scourge Enchantment, and Restful Breeze. Cast retribution before the battle and leave it up for the entire battle.  Use shield of judgment as often as the cooldown allows.  Use scourge enchantment often enough to keep it on doppelganger constantly, as this will ensure that even with the divine favor healing, doppelganger's casts give it roughly no net healing.  Keep restful breeze on yourself most of the time, and do not attack, as this will end restful breeze.  Retribution and shield of judgment do enough damage to kill doppelganger in well under 2 minutes.

Necromancer

 * Bring spells that require a health sacrifice. Don't use these skills yourself, but rather let the Doppelganger use them. By including Awaken the Blood or Cultist's Fervor as the first skills in your skill bar, the Doppelganger will use them first, thereby increasing the health sacrifice. The elite skill Order of the Vampire is a very good choice for this role. With a 17% max health sacrifice and a 5 second cooldown, the Doppelganger is likely to kill itself in seconds. With Monk as your secondary profession, Scourge Sacrifice works wonders with this strategy.


 * Take skills that inflict conditions upon yourself, such as Signet of Agony and Chilblains. Don't use them yourself, let the Doppelganger use them, giving itself conditions such as poison and bleeding, while you only take a small amount of damage.


 * Anti-melee hexes like Spiteful Spirit, Insidious Parasite and Reckless Haste make killing the Doppelganger a lot easier. Cast the hexes on it, and let it kill itself. Be sure to not attack it with these hexes on you.


 * Don't bring life steal skills or hexes such as Life Siphon and Life Transfer. The Doppelganger will likely also cast them on you, so at best it will be an even trade and cancel out.


 * Remember that there will be nothing dying in this battle, so not only will Soul Reaping be worthless, anything that requires a corpse (such as any well spells, any minions, Soul Feast, Consume Corpse, Necrotic Traversal, etc.) will do you no good.

Hard Mode Notes


 * Anti-melee hexes work wonders.
 * The 55 Necro solo build works very well. You must cast enchantments before the cutscene and as soon as you enter cast protective spirit, SS, and insidious parasite, and hop into melee range. You will have to recast these as necessary.

Ranger

 * Bring many slow-casting Nature Rituals like Favorable Winds and Quickening Zephyr. The Doppelganger will waste time casting the rituals while you attack.


 * Equip bow attacks and stay within melee range of the Doppelganger; it will switch to its axe and thus be unable to use the bow attacks.


 * Alternatively, get your pet to do all the damage. Skills like Enraged Lunge, Call of Protection and Symbiotic Bond work pretty good. To prevent taking too much damage, try to hide behind a wall and let your pet do the dirty work. Another way is to just bring the skill charm animal, a high level pet along with a few arrows should defeat Doppelganger easily.

Hard Mode Notes


 * Even in Hard Mode, the Doppelganger will try to use any spirits before attacking. Use this to your advantage.


 * Toxicity, Poisonous Bite and Scavenger Strike is a great combo if you have all three campaigns and a high-level pet. Let the Doppelganger cast Toxicity for you. Keep it poisoned and spam Scavenger Strike.

Warrior

 * Equip Frenzy, but don't use it. The Doppelganger will, putting itself at a significant disadvantage. Couple this with a few attack skills, preferably energy-based so you  use them right away, and it will go down very quickly.


 * The Doppelganger does not use a shield, so bringing skills that require a shield (such as Shield Stance and Shield Bash) gives a significant advantage.


 * Equip an attack combo from left to right in reverse order (such as Final Thrust, Gash, Sever Artery). The Doppelganger doesn't understand the order certain skills should be used in, and prioritizes them from left to right on the bar when they are charged.


 * Any skills that cause you to lose all adrenaline (such as Wild Blow) can be a great benefit. Ignore them yourself and let the Doppelganger waste its own adrenaline using them on you.

Hard Mode Notes


 * An easy method to kill the Doppelganger is to use block skills like Riposte, Deadly Riposte and Gladiator's Defense. Stand close to the Doppelganger so it can attack you with its axe, and block all its attacks.


 * The 'attack chain in reverse order' strategy will not work on Hard Mode.


 * The Doppelganger will not use Frenzy.

Ritualist

 * A build which relies on a lot of spirits can work quite well, if you can prevent the Doppelganger from putting down the spirits. A good choice would be Dissonance, or perhaps Warmonger's Weapon.


 * An easy victory can be achieved by using the skills Vengeful Weapon combined with either Weapon of Remedy or Vengeful Was Khanhei. Let the Doppelganger attack you have these skills on you, but do not attack back.


 * Take useless spirits like Recovery, and let the Doppelganger waste its time casting the spirits while you kill it with Channeling Magic spells.

Hard Mode Notes


 * Vengeful Weapon combined with Vengeful Was Khanhei is a reliable tactic.

Assassin

 * Assassins have plenty of options to defeat the Doppelganger. By equipping Vampiric Daggers with high Critical Strikes and Dagger Mastery, you can easily kill it simply by attacking and without even using skills.


 * Don't take any Dual Attacks, but include hexes that trigger on them to have the Doppelganger waste its time and energy casting them.


 * As a general rule, if you can start a dagger chain that you can use but the Doppelganger will not, it is quite easy to out damage it.


 * Bring Deadly Paradox and some attack skills. It will disable its attack skills with Deadly Paradox, while you take advantage of them.


 * Shadow Walk is a good choice, combined with several enchantments that keep you alive. If the Doppelganger uses Shadow Walk, it will not be able to cast the enchantments.

Hard mode notes


 * Bring Shadow Form and Expunge Enchantments and get Doppelganger to waste the latter on a useless enchantment. Use shadow form yourself when you get low on life, and when the Doppelganger gets low on life and uses shadow form, remove it. This gives you more time to kill the Doppelganger than it has to kill you.

Paragon

 * Use a lot of Spear Attacks, and stay in melee range. The Doppelganger will use its axe, and will not be able to use these attack skills.


 * Equip chants that have an effect based on spell casting, such as Aria of Zeal or Aria of Restoration. The Doppelganger will waste time and energy using these for no benefit.

Dervish

 * With high scythe mastery and using Vow of Strength, you can easily defeat the Doppelganger by simply attacking it.


 * Bring Vow of Silence, Heart of Holy Flame, Zealous Renewal or Balthazar's Rage, Grenth's Fingers, Dust Cloak, Mystic Twister, and Mystic Sandstorm. Put all of your attribute points into Mysticism, Earth Prayers, and Wind Prayers; Mysticism is the most important. You'll need a staff with +15 or more energy on it and possibly extra energy from runes. The Doppelganger will start off by casting Vow of Silence, which means it cannot use any other spells, then you can use your skills in this order: Heart of Holy Flame, Zealous Renewal, Grenth's Fingers, Dust Cloak, Mystic Twister, Mystic Sandstorm. All of these skills will go through the Doppelganger's Vow of Silence since they are not targeted. If Mystic Sandstorm doesn't finish it off, the burning from Heart of Holy Flame will.


 * If you have Ranger as your secondary profession, bring Avatar of Lyssa and as many slow-casting, useless spirits as possible. The Doppelganger will cast the spirits while you attack with Avatar of Lyssa on.


 * A few high damage attacks (such as Reaper's Sweep, Irresistible Sweep, Pious Assault, or Victorious Sweep) should be enough to quickly overpower the Doppelganger before it can do the same to you.

Hard Mode Notes


 * For Hard Mode, the tactics described above are usually not sufficient, as the Doppelganger simply outdamages you. A good way of defeating the Doppleganger is to use Ebon Dust Aura with an Earth weapon. The Doppelganger will not be able to take advantage of Ebon Dust Aura, but you can. Try to keep it blind as much as possible, and kill it with your scythe.