Writhing Necromass

This spell costs {1} less to cast for each creature card in your graveyard.
Deathtouch

Sneaky Snacker

Flying
When you draw your third card in a turn, return Sneaky Snacker from your graveyard to the battlefield tapped.

Echo of Dusk

Descend 4 — As long as there are four or more permanent cards in your graveyard, Echo of Dusk gets +1/+1 and has lifelink.

Wight of Precinct Six

Wight of Precinct Six gets +1/+1 for each creature card in your opponents' graveyards.

Tolarian Winds

Discard all the cards in your hand, then draw that many cards.

Entropic Decay

Mill four cards. (Then exile this card. You may cast the creature later from exile.)

Gray Slaad

As long as there are four or more creature cards in your graveyard, Gray Slaad has menace and deathtouch.

Gray Slaad // Entropic Decay

Liliana's Elite

Liliana's Elite gets +1/+1 for each creature card in your graveyard.

Moodmark Painter

Undergrowth — When Moodmark Painter enters, target creature gains menace and gets +X/+0 until end of turn, where X is the number of creature cards in your graveyard. (It can't be blocked except by two or more creatures.)

Driver of the Dead

When Driver of the Dead dies, return target creature card with mana value 2 or less from your graveyard to the battlefield.