If you can fit Plunge into Darkness mainboard, it acts as either instant speed Death's Shadow buff, or emergency life gain. Replacing itself with one of X cards is also a pretty nifty benefit :)
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Tainted strike can be either avoidance or to make a bomb (e.g. low life, opponent about to kill you, you give them +1/+0 and infect so you don't take the damage to your life total, or you win using infect on a demon of death's gate when they don't block). The main point is to accumulate so much card advantage, and get out Death's Shadow at a high power early, that you don't worry about the fact that you're killing yourself, as well as relying on bombs endgame if it ends up going that far (always have multiple win conditions). If Dark Tutelage was a may effect, it'd be ideal, but, this deck is mostly for fun/casual.