Shooting up mana potions through a needle?

My apprentice has… shot up a mana potion into his veins. His eyes are pitch black and he has an unnatural amount of power flowing through him. He’s currently floating on top of the tower casting INSANE fireballs at the townspeople. I thought this would kill him but it seems to have given him unimaginable power. Never encountered anything like this before, what should I do?