{3}{U}, Exile Shifty Doppelganger: You may put a creature card from your hand onto the battlefield. If you do, that creature gains haste until end of turn. At the beginning of the next end step, sacrifice that creature. If you do, return Shifty Doppelganger to the battlefield.
Flying At the beginning of your upkeep, mill a card. Threshold — As long as seven or more cards are in your graveyard, Bloodcurdler gets +1/+1 and has "At the beginning of your end step, exile two cards from your graveyard."
Threshold — {1}{B}, {T}, Exile two cards from your graveyard: Target player discards a card. Activate only as a sorcery and only if seven or more cards are in your graveyard.
{2}{B}, Sacrifice a creature: Target creature gets -2/-2 until end of turn. {2}{B}, Exile a creature card from your graveyard: Target creature gets -2/-2 until end of turn.