Unruly Mob

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

Voracious Vermin

When Voracious Vermin enters, create a 1/1 black Rat creature token with "This creature can't block."
Whenever another creature you control dies, put a +1/+1 counter on Voracious Vermin.

Gimli, Mournful Avenger

Gimli, Mournful Avenger has indestructible as long as two or more creatures died under your control this turn.
Whenever another creature you control dies, put a +1/+1 counter on Gimli. When this ability resolves for the third time this turn, Gimli fights up to one target creature you don't control.

Flaming Fist Officer

Whenever another creature you control leaves the battlefield, put a +1/+1 counter on Flaming Fist Officer.

Feral Ghoul

Menace
Whenever another creature you control dies, put a +1/+1 counter on Feral Ghoul.
When Feral Ghoul dies, each opponent gets a number of rad counters equal to its power.

Rising Populace

Whenever another creature or planeswalker you control dies, put a +1/+1 counter on Rising Populace.

Rockslide Elemental

First strike
Whenever another creature dies, you may put a +1/+1 counter on Rockslide Elemental.

Ninth Bridge Patrol

Whenever another creature you control leaves the battlefield, put a +1/+1 counter on Ninth Bridge Patrol.

Taborax, Hope's Demise

Flying
Taborax, Hope's Demise has lifelink as long as it has five or more +1/+1 counters on it.
Whenever another nontoken creature you control dies, put a +1/+1 counter on Taborax. If that creature was a Cleric, you may draw a card. If you do, you lose 1 life.

Cordial Vampire

Whenever Cordial Vampire or another creature dies, put a +1/+1 counter on each Vampire you control.

Rot Shambler

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