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Keeper of the Dead
{B}{B}
Creature -- Human Wizard
1/2
{B}, {T}: Choose target opponent who has at least two fewer creature cards in their graveyard than you do as you activate this ability. Destroy target nonblack creature that player controls.

Throat Slitter
{4}{B}
Creature -- Rat Ninja
2/2
Ninjutsu {2}{B} ({2}{B}, Return an unblocked attacker you control to hand: Put ~this~ onto the battlefield from your hand tapped and attacking.)
Whenever ~this~ deals combat damage to a player, destroy target nonblack creature that player controls.