This is a general guide on how to kill Belial, the Lord of Lies and can be used for all difficulties. Belial is the last boss of Act 2 and can be really though some times, so knowing the right strategy for both phases is important.
The Belial Fight has two phases . The first one is usually pretty easy, but the second can be tricky.
Phase 1 : Kill all the mobs that spawn until you can attack Belial, attack him until he has about 25% HP left.
Phase 2: This is where you have to be careful. Ranged classes will have an easier time, because they can do DPS while moving away from his attacks.
When Belial tries to smash you, avoid the green spot on the ground and you should stay safe.
When he uses his breath attack move to the opposite direction and stay away from the attack as much as possible.
Run away from the explosions and try not to get cornered.
When you’ve avoided his attacks, do as much damage in between attacks as you can. Do this until you’ve killed him.