Belial is one of the lesser evils and he is the boss of the Act 2 in Diablo 3, a tough boss if you ask me because actually he has 2 phases where you have to pay attention and be careful because otherwise you will end up dead. In this article i will try to guide you in the fight with Belial, the Lord of Lies. I will cover how to solo but also some tips if you will try to defeat it playing with your friends, because in a party is a bit harder if you don't coordinate well.
As i said, Belial has 2 phases and the hardest one is the second phase, basically the first phase is really easy as you just have to kill the guards and then you will be able to attack him. In that moment, ignore any other minions and go fully DPS on Belial. At 25% hp he will go into a rage mode and that's the moment when you will see the phase 2 of Belial, where you really have to pay attention to his special abilities otherwise you will end up dead. The key in how to kill Belial in Diablo 3, is to counter his spells with your defensive abilities.