This is location where the lonely add should be pulled and where rest of group stack. All other adds should be chained in here. With two tanks one should chain front and other from left. Fight is long so use horn or two before saving one for manti. Tank manti somehow in middle of room near water to make enough space for people for dodging quakes. Quakes, triple AOE, generally you should be fine eating all of them given you get heals. Multiple people get them so watch out if noone is running into you. Stomp attack. Portal phase. It spawns under random person. People should be spread out to control who gets in (it should be off tank and dps). You can actually see visial indicator on who it spawns before it sucks people in.
Spears land on people furthest away from boss. They snare and damage. If it happens that they start stacking too close to group boss needs to be pulled away. This what happens when portal lands on you. Off tank takes over boss while you go down. Keep in mind that manti dot is on you so self heal as soon as you get down. Tank miniboss faced away from DPS. When you return to surface its usually better to stay off tanking meaning vigor group, igneous shield when you see someone getting quaked, res people..
As found on Youtube