Thirsty River (mission)

Ok, as I said, everyone has the hardest time with this, what you will need is a completely dedicated healer, a secondary healer, two elementalists with meteor and other high damage spells, and I'd say a few warrior types that can keep themselves and others alive a bit longer.

From the start, get the Sand Giant immediately at your west, he should be alone, bring him back and kill him, they use necromancy spells and giant stomp, but aren't much of a burden solo. This will give you a 2% morale boost, there are 5 out here, however, you really only need to kill 4 for the full bonus, since one of them is out of its way through a bunch of devourers. Instead, you can gain that total of 10 through the first boss you'll need to defeat, which won't be very hard.

Continue on the obvious path forward, which would be mostly south towards a passage over a wrecked ship or something, a few devourers should be in your way to the next giant. Continue along the path over the ship and you'll fight another set of devourers, and soon make your way into an oasis of sorts. Pull the devourers out and then engage the Sand Giant on the ledge, and the fourth which should be just further along the pathway, and you'll be to your first encounter of the mission, or as I call it, Morale Boost Full.

Ghostly hero will activate it, and the timer will begin counting up; don't feel pressured, that is the first thing I must say, but do move fast basically, there is no reason to dawdle around. The first group of two or three, mostly enchanteds, should go down before 45 seconds has passed, and move quickly on to the illusions or arcanists outside of the bosses quarters. Try not to fight with the Boss at the same time, but, it won't matter much if you do. You need to be at the Boss and Priest alone at least by 1:30, at which time everyone hit the priest as hard as possible, meteors away, knockdowns and such are good. He isn't strong, but can keep himself healed if not properly dealt with, and at 2:00 minutes will resurrect all of the downed enemies in his group, that last portion is more a note for the next few groups as he won't be resurrecting other enemies don't worry. The boss is random, but tends to have alot of hp but not much damage to him, kill at your leisure and move on to the next fight.

Before moving too far along this path, talk to the hero to see who he is following. This is an exploit so don't think it is the best way to approach the situation, but, hold the ghostly hero back. From here, you can lay into the enemy groups without setting the timer, the second the hero goes near, this timer starts, so you could potentially have all your enemies down. I suggest the right side (aka northern) as you get a heightened range and should be able to down both infact before starting. Time the ghostly hero to be at the door as the first southern group is moving away, since it will take a few seconds for the doors to actually open, and you can run right to the priest, kill him and the boss. Teams wanting a bit more challenge can kill that other patrol at the door and try to kill the priest of the cleared team,then the group and priest of the other before the first 2:00 has passed.

After the first boss and priest is dead, you'll probably easily be at 45 seconds, don't press your luck and go running off to try and kill people in 1:15, this is how groups die here. Get a fresh 2 minutes to go on, at least 1:50 as I've seen groups draw this awfully close to respawn, which can mean disaster for your group with two groups and a boss after a quick moving fight to just get in there. You can also from the northern group stick to the wall and avoid the closer group, then rush the priest and go on your way to the last challenge.

You guessed it, 3 groups at once. Hold back once again, and try to kill the right, or nothern, groups first before heading in, others will be useless to get. Move in, go to that area quickly, you should be able to avoid the patrol and get the priest before having to fight others, but you will want to eliminate them.

The bonus here is I think defeating all three teams in like 5:00, but, unless you are with a group whos purpose is to do that rather than ascend (as in you already have), don't try, even moving very quick can still take you over this. From here, you already have the tactics for beating the next two teams, just defeat one then the next, making sure to get a fresh start of 2:00 on each fight.

A little side note which some teams fail to realize, if you are fearful of a respawn and have say only 20 or 15 seconds, back up, the patrols will move out and you can start again. Running in there to try to throw everythign at the priest only to be caught in that respawn is a sure way to fail, which means restarting the entire mission, as opposed to just that boss.