Medomai the Ageless

Flying
Whenever Medomai the Ageless deals combat damage to a player, take an extra turn after this one.
Medomai the Ageless can't attack during extra turns.

Elenda, the Dusk Rose

Lifelink
Whenever another creature dies, put a +1/+1 counter on Elenda, the Dusk Rose.
When Elenda dies, create X 1/1 white Vampire creature tokens with lifelink, where X is Elenda's power.

Nightmare Shepherd

Flying
Whenever another nontoken creature you control dies, you may exile it. If you do, create a token that's a copy of that creature, except it's 1/1 and it's a Nightmare in addition to its other types.

Void Rend

This spell can't be countered.
Destroy target nonland permanent.

Evil Twin

You may have Evil Twin enter as a copy of any creature on the battlefield, except it has "{U}{B}, {T}: Destroy target creature with the same name as this creature."

Reveillark

Flying
When Reveillark leaves the battlefield, return up to two target creature cards with power 2 or less from your graveyard to the battlefield.
Evoke {5}{W} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Grim Haruspex

Morph {B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
Whenever another nontoken creature you control dies, draw a card.

Ratadrabik of Urborg

Vigilance, ward {2}
Other Zombies you control have vigilance.
Whenever another legendary creature you control dies, create a token that's a copy of that creature, except it's not legendary and it's a 2/2 black Zombie in addition to its other colors and types.

Keiga, the Tide Star

Flying
When Keiga, the Tide Star dies, gain control of target creature.

Midnight Reaper

Whenever a nontoken creature you control dies, Midnight Reaper deals 1 damage to you and you draw a card.

The Ever-Changing 'Dane

{1}, Sacrifice another creature: The Ever-Changing 'Dane becomes a copy of the sacrificed creature, except it has this ability.

Solemn Simulacrum

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

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Bane, Lord of Darkness

As long as your life total is less than or equal to half your starting life total, Bane, Lord of Darkness has indestructible.
Whenever another nontoken creature you control dies, target opponent may have you draw a card. If they don't, you may put a creature card with equal or lesser toughness from your hand onto the battlefield.

Morbid Opportunist

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