Probably because its a boss (otherwise they can run out of mana)
Imagine just how boring can be a battle if your boss run out of mana... (unless of course thats the mechanic of the boss) He will sit there looking at you... recalling the old days when he had mana! :D
 "The Great War of Prefectures"){kind=icon}
 "Champions Of Chaos 2"){kind=icon}
 "Mecha Arena"){kind=icon}
Probably because its a boss (otherwise they can run out of mana) Imagine just how boring can be a battle if your boss run out of mana... (unless of course thats the mechanic of the boss) He will sit there looking at you... recalling the old days when he had mana! :D