In Act V of Diablo III there are three total act bosses and they scale proportionally in difficulty. For those who are used to soloing in the torment levels, you may find some difficulty in approaching Malthael towards the end. For my group, he was nearly impossible even on Master, so do understand that these bosses grow in strength rather quickly.
Boss I: Urzael, Harbinger of Death
This dude is the easiest boss because he stops a lot to cast and you can avoid his damage rather easily. HeÂs got a few attacks; primarily youÂre going to be avoiding the targeting reticles on the ground for most of the fight. His first attack is a simple melee attack where he tries to smack you with his flamethrower.
His next attack is a jump attack. YouÂll see a single red circle on the ground, thatÂs where heÂs going to jump to. This one hurts quite a bit. Likewise, with no warning, heÂs got a flamethrower ability that he circles around with that hurts like any other flame / laser (think a mobile furnace).
He also has another attack where he shoots a line of fire out. Easily avoided.
His final attack is a simple mortor attack, where he launches projectiles in the air that come crashing down. Just avoid standing in any red circles on the ground.
This fight is fairly simple. Avoid any red circles on the ground, watch out for his flamethrower, and keep your distance whenever heÂs not casting a spell (if youÂre melee). IÂve heard of a lot of complaints about melee having difficulty in this fight and a lot of times itÂs them trying to face tank his flamethrower which isnÂt going to work. He canÂt flamethrow if heÂs charging another ability, so avoid dying and whack him when you have an opening.
Also, again, red markers are going to illustrate where parts of the room are going to be falling down leaving burning debris as well. Try to avoid these, but for me they didnÂt hurt that bad, so IÂd rather avoid direct damage from the boss than the environmental damage in this fight.
Boss II: Adria, The Witch
She is a bit simpler and I donÂt know for just a little bit harder on Torment II. Anyway, sheÂs got only a few abilities and primarily melees. The first is she can spawn bloodworms which if you walk over them, they explode and put down a pool of blood that do environmental damage (and hurt really bad when they explode to) so try to avoid those.
Next, she random disappears whenever she feels like and reappears elsewhere. This can cause you if youÂre melee to accidentally walk over bloodworms if youÂre clicking like mad. So watch out for that.
SheÂs got an AoE cleave, so obviously donÂt pile up around her.
Boss III: Malthael
Malthael is really tough. Like, insanely tough. As in if youÂre just a fresh level 70 youÂre going to probably kill him on hard tough. So prepare for that and donÂt feel bad if you strolled through at torment II or III as you leveled up and then you get to him and he just owns your face.
Anyway, biggest issue is just the damage he does. He attacks fast and has a charge attack to get up close and personal rather quickly.
So things to be aware of. He can put clouds on the ground (or mist or whatever you want to call it) that hurts. He will teleport to the center and throw out fire or bloodballs (not specifically sure which) which explode near the outer area of the arena and put environmental damage down. Then he shoots blood spears out everywhere which are very hard to avoid.
HeÂs got a permanent AoE cleave going on too.
My best advice for this fight is just try to avoid everything and attack when you can. Treat it more like a shmup than an actual boss fight, because mitigating his damage is way more important than attacking.