Bounty Hunter

{T}: Put a bounty counter on target nonblack creature.
{T}: Destroy target creature with a bounty counter on it.

Squee's Toy

{T}: Prevent the next 1 damage that would be dealt to target creature this turn.

Horobi, Death's Wail

Flying
Whenever a creature becomes the target of a spell or ability, destroy that creature.

Cabal Torturer

{B}, {T}: Target creature gets -1/-1 until end of turn.
Threshold — {3}{B}{B}, {T}: Target creature gets -2/-2 until end of turn. Activate only if there are seven or more cards in your graveyard.

Banshee

{X}, {T}: This creature deals half X damage, rounded down, to any target, and half X damage, rounded up, to you.