Its a little overpowered, but I love the design.
How about "Battlecry: Choose a minion. It takes 1 damage at the end of each turn." If that's not strong enough, maybe the damage could increase each turn. Not that much of an change, since minions usually don't live long enough for it to matter, but it could occasionally save you against cards like Ysera. Although, the original design has the best synergy with Acolyte of Pain.