Termination Facilitator

{T}: Put a bounty counter on target creature or planeswalker. Activate only as a sorcery.
Whenever a creature or planeswalker an opponent controls with a bounty counter on it is dealt damage, destroy it.

Wei Assassins

When Wei Assassins enters, target opponent chooses a creature they control. Destroy that creature.

Massacre Girl

Menace
When Massacre Girl enters, each other creature gets -1/-1 until end of turn. Whenever a creature dies this turn, each creature other than Massacre Girl gets -1/-1 until end of turn.

Blood Cultist

{T}: Blood Cultist deals 1 damage to target creature.
Whenever a creature dealt damage by Blood Cultist this turn dies, put a +1/+1 counter on Blood Cultist.

Royal Assassin

Kelsien, the Plague

Vigilance, haste
Kelsien, the Plague gets +1/+1 for each experience counter you have.
{T}: Kelsien deals 1 damage to target creature you don't control. When that creature dies this turn, you get an experience counter.

Lurking Deadeye

Flash
When Lurking Deadeye enters, destroy target creature that was dealt damage this turn.

Mirrodin Avenged

Destroy target creature that was dealt damage this turn.
Draw a card.

You Are Already Dead

Gorgon's Head

Equipped creature has deathtouch.
Equip {2}

Hooded Assassin

When Hooded Assassin enters, choose one —
• Put a +1/+1 counter on Hooded Assassin.
• Destroy target creature that was dealt damage this turn.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Serpent Assassin

When Serpent Assassin enters, you may destroy target nonblack creature.

King's Assassin

{T}: Destroy target tapped creature. Activate only during your turn, before attackers are declared.

Stingblade Assassin

Flash
Flying
When Stingblade Assassin enters, destroy target creature an opponent controls that was dealt damage this turn.

Gorgon Flail

Equipped creature gets +1/+1 and has deathtouch. (Any amount of damage it deals to a creature is enough to destroy that creature.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Death Pits of Rath

Whenever a creature is dealt damage, destroy it. It can't be regenerated.

Sol Ring

Rathi Assassin

{1}{B}{B}, {T}: Destroy target tapped nonblack creature.
{3}, {T}: Search your library for a Mercenary permanent card with mana value 3 or less, put it onto the battlefield, then shuffle.