Sidisi, Brood Tyrant

Whenever Sidisi, Brood Tyrant enters the battlefield or attacks, mill three cards.
Whenever one or more creature cards are put into your graveyard from your library, create a 2/2 black Zombie creature token.

Circle of the Land Druid

When Circle of the Land Druid enters the battlefield, you may mill four cards. (You may put the top four cards of your library into your graveyard.)
Natural Recovery — When Circle of the Land Druid dies, return target land card from your graveyard to your hand.

Fetch Quest

Mill seven cards. Then put a creature, enchantment, or land card from among the milled cards onto the battlefield.

Bramble Familiar

{T}: Add {G}.
{1}{G}, {T}, Discard a card: Return Bramble Familiar to its owner's hand.

Bramble Familiar // Fetch Quest

Can't Wake Up

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

Cruel Somnophage

Cruel Somnophage's power and toughness are each equal to the number of creature cards in all graveyards.

Cruel Somnophage // Can't Wake Up

Deathcap Marionette

Deathtouch
When Deathcap Marionette enters the battlefield, you may mill two cards. (You may put the top two cards of your library into your graveyard.)

Aftermath Analyst

When Aftermath Analyst enters the battlefield, mill three cards.
{3}{G}, Sacrifice Aftermath Analyst: Return all land cards from your graveyard to the battlefield tapped.

Acolyte of Affliction

When Acolyte of Affliction enters the battlefield, mill two cards, then you may return a permanent card from your graveyard to your hand.

Blanchwood Prowler

When Blanchwood Prowler enters the battlefield, mill three cards. You may put a land card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on Blanchwood Prowler. (To mill a card, put the top card of your library into your graveyard.)

Crow of Dark Tidings

Flying
When Crow of Dark Tidings enters the battlefield or dies, mill two cards. (Put the top two cards of your library into your graveyard.)

Flayed One

Lifelink
Flesh Flayer — When Flayed One enters the battlefield, mill three cards.

Ghostly Castigator

Flying
When Ghostly Castigator enters the battlefield, you may shuffle up to three target cards from your graveyard into your library.
If Ghostly Castigator would be put into a graveyard from anywhere, exile it instead.

Covetous Castaway

When Covetous Castaway dies, mill three cards. (Put the top three cards of your library into your graveyard.)
Disturb {3}{U}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Covetous Castaway // Ghostly Castigator

Glowspore Shaman

When Glowspore Shaman enters the battlefield, mill three cards. You may put a land card from your graveyard on top of your library. (To mill a card, put the top card of your library into your graveyard.)

Deranged Assistant

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