Billowing Shriekmass

Flying
When this creature enters, mill three cards. (Put the top three cards of your library into your graveyard.)
Threshold — This creature gets +2/+1 as long as there are seven or more cards in your graveyard.

Revenge of the Rats

Create a tapped 1/1 black Rat creature token for each creature card in your graveyard.
Flashback {2}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tragic Banshee

Morbid — When this creature enters, target creature an opponent controls gets -1/-1 until end of turn. If a creature died this turn, that creature gets -13/-13 instead.

Gutless Plunderer

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Raid — When this creature enters, if you attacked this turn, look at the top three cards of your library. You may put one of those cards back on top of your library. Put the rest into your graveyard.

Midnight Snack

Raid — At the beginning of your end step, if you attacked this turn, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
{2}{B}, Sacrifice this enchantment: Target opponent loses X life, where X is the amount of life you gained this turn.

Crypt Feaster

Menace (This creature can't be blocked except by two or more creatures.)
Threshold — Whenever this creature attacks, if there are seven or more cards in your graveyard, this creature gets +2/+0 until end of turn.