Bitterblossom

At the beginning of your upkeep, you lose 1 life and create a 1/1 black Faerie Rogue creature token with flying.

Mari, the Killing Quill

Whenever a creature an opponent controls dies, exile it with a hit counter on it.
Assassins, Mercenaries, and Rogues you control have deathtouch and "Whenever this creature deals combat damage to a player, you may remove a hit counter from a card that player owns in exile. If you do, draw a card and create two Treasure tokens."

Morbid Opportunist

Whenever one or more other creatures die, draw a card. This ability triggers only once each turn.

Changeling Outcast

Changeling (This card is every creature type.)
This creature can't block and can't be blocked.