Thundering Raiju

Haste
Whenever this creature attacks, put a +1/+1 counter on target creature you control. Then this creature deals X damage to each opponent, where X is the number of modified creatures you control other than this creature. (Equipment, Auras you control, and counters are modifications.)

Thran Vigil

Whenever one or more artifact and/or creature cards leave your graveyard during your turn, put a +1/+1 counter on target creature you control.

Counterspell

Marchesa, the Black Rose

Dethrone (Whenever this creature attacks the player with the most life or tied for most life, put a +1/+1 counter on it.)
Other creatures you control have dethrone.
Whenever a creature you control with a +1/+1 counter on it dies, return that card to the battlefield under your control at the beginning of the next end step.

Voldaren Thrillseeker

Backup 2 (When this creature enters, put two +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.)
{1}, Sacrifice this creature: It deals damage equal to its power to any target.

Scorn-Blade Berserker

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
{1}, Sacrifice this creature: Draw a card.

Solemn Simulacrum

When this creature enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When this creature dies, you may draw a card.

Iron Apprentice

This creature enters with a +1/+1 counter on it.
When this creature dies, if it had counters on it, put those counters on target creature you control.

Yahenni, Undying Partisan

Haste
Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni.
Sacrifice another creature: Yahenni gains indestructible until end of turn.