Wheel of Misfortune + Barbed Servitor + Pariah's Shield
Wheel of Misfortune
Barbed Servitor
Pariah's Shield
Near-infinite lifeloss for target opponent
How it works
Cast Wheel of Misfortune by paying 2, choosing an arbitrarily large number and having Wheel of Misfortune deal that much damage to Barbed Servitor instead of you due to Pariah's Shield if you chose the largest number.
Barbed Servitor triggers, causing an opponent to lose life equal to the damage dealt.