The Lord of Sin rules over a densely populated land of hell where both the greatest joys and despair, and the deepest depravities can be experienced. But it is never enough for Azmodan, who has set his eyes on the realm of Sanctuary.
As with all the Evils, Azmodan originated from one of the seven heads of Tathamet. He lorded over the Realm of Sin. For much of his existence he desired to be the sole ruler of Hell.
During the Great Conflict, Azmodan successfully defeated his angelic foes many times on the battlefields of Pandemonium. In one such battle, Azmodan faced the archangel Tyrael. Tyrael bested him and stood ready to deal the final blow. However, one of Tyrael's comrades called for aid and Tyrael rushed to lend aid. Azmodan thus escaped the angel's wrath.
Low mobility prevents Azmodan from escaping from a situation where he has been overextended or when his abilities are on cooldown
Long cooldowns leave Azmodan vulnerable if he has recently used all his abilities.
Although capable of dealing very high sustained damage, he can't really contribute to teamfights until level 13 and building purely into All Shall Burn and Demonic Invasion. Even then, his damage is focused on one target and relies on him not being stunned or silenced and being able to channel long enough for his E to do any real damage.
Even though his Q has a very long range, it has a long travel time when used at longer ranges, even with Infernal Globe; meaning he'll have to predict exactly where his target is going to be.
Channel a death beam on an enemy dealing 100 (+4% per level) damage a second. The damage amount grows the longer it is channeled, to a maximum of 200 (+4% per level) damage per second. Does 25.00% more damage to Structures. Azmodan can move at 40% speed while channeling.
Summon a Demon Lieutenant at an allied Mercenary, Minion, or Azmodan's Summons. The Lieutenant will march with the target, granting 25% increased damage to all nearby friendly Mercenaries, Minions, and Azmodan's Summons. Unlimited range.
Having a unusual high health for a non-Warrior, Azmodan's limited movement and lack of crowd control allows Malthael to stick on him. Additionally, Azmodan's ability to summon minions means Malthael can get extra health from Soul Rip.