Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Krosan Beast

Threshold — Krosan Beast gets +7/+7 as long as seven or more cards are in your graveyard.

Werebear

{T}: Add {G}.
Threshold — Werebear gets +3/+3 as long as seven or more cards are in your graveyard.

Psychatog

Discard a card: Psychatog gets +1/+1 until end of turn.
Exile two cards from your graveyard: Psychatog gets +1/+1 until end of turn.

Traumatize

Target player mills half their library, rounded down.

Metamorphic Wurm

Threshold — Metamorphic Wurm gets +4/+4 as long as seven or more cards are in your graveyard.

Forest

Nimble Mongoose

Shroud (This creature can't be the target of spells or abilities.)
Threshold — Nimble Mongoose gets +2/+2 as long as seven or more cards are in your graveyard.

Zombify

Return target creature card from your graveyard to the battlefield.

Laquatus's Creativity

Target player draws cards equal to the number of cards in their hand, then discards that many cards.

Bloodcurdler

Flying
At the beginning of your upkeep, mill a card.
Threshold — As long as seven or more cards are in your graveyard, Bloodcurdler gets +1/+1 and has "At the beginning of your end step, exile two cards from your graveyard."