What is your vote for the most overpowered spell in the game?

[MaroonMaurader]

I'd like to put forward Mana Spring, at least for those trying for a no-loss game. Stoneskin isn't good unless you can get 55% physical resistance from other items, so by itself it isn't overpowered. Target is good, but not stellar unless you're comboing it with a turn-back-time or with a high-resistance setup (stoneskin + other resistances for example). Mana spring, all by itself, can transform most victories into no-loss victories.