Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Gravecrawler

This creature can't block.
You may cast this card from your graveyard as long as you control a Zombie.

Emry, Lurker of the Loch

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
When Emry enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Shriekhorn

This artifact enters with three charge counters on it.
{T}, Remove a charge counter from this artifact: Target player mills two cards.

Stitcher's Supplier

When this creature enters or dies, mill three cards. (Put the top three cards of your library into your graveyard.)