Apocalypse deals strong Almighty AOE damage while having a high mute chance for a low MP cost.
Access to Concentrate to further increase his damage.
No weaknesses and 2 Nulls give him a lot of flexibility in skill transfers.
Cons
Mute from Apocalypse is blocked by Barrier, requires a teammate with Barrier Break or P2 to effectively work.
Apocalypse does not get higher damage from leveling up the skill or from Panels, and as an Almighty skill can only be boosted by passives such as Butcher, Serial Killer...