Wreath of Geists

Enchant creature
Enchanted creature gets +X/+X, where X is the number of creature cards in your graveyard.

Memory's Journey

Target player shuffles up to three target cards from their graveyard into their library.
Flashback {G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Boneyard Wurm

Boneyard Wurm's power and toughness are each equal to the number of creature cards in your graveyard.

Spectral Flight

Enchant creature
Enchanted creature gets +2/+2 and has flying.

Tracker's Instincts

Reveal the top four cards of your library. Put a creature card from among them into your hand and the rest into your graveyard.
Flashback {2}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Armored Skaab

When Armored Skaab enters, mill four cards.

Frost Breath

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.

Splinterfright

Trample
Splinterfright's power and toughness are each equal to the number of creature cards in your graveyard.
At the beginning of your upkeep, mill two cards.

Ghoultree

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

Homicidal Brute

At the beginning of your end step, if Homicidal Brute didn't attack this turn, tap Homicidal Brute, then transform it.

Civilized Scholar

{T}: Draw a card, then discard a card. If a creature card is discarded this way, untap Civilized Scholar, then transform it.