Death Watch

Enchant creature
When enchanted creature dies, its controller loses life equal to its power and you gain life equal to its toughness.

Silumgar Scavenger

Flying
Exploit (When this creature enters, you may sacrifice a creature.)
Whenever another creature you control dies, put a +1/+1 counter on this creature. It gains haste until end of turn if it exploited that creature.

Deathgreeter

Whenever another creature dies, you may gain 1 life.

Warteye Witch

Whenever this creature or another creature you control dies, scry 1.

Phyrexian Vivisector

Whenever a creature you control dies, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Horobi, Death's Wail

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

Gavony Unhallowed

Whenever another creature you control dies, put a +1/+1 counter on this creature.