Undercity Informer

{1}, Sacrifice a creature: Target player reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

Ghoulcaller's Bell

Eye Collector

Flying
Whenever Eye Collector deals combat damage to a player, each player mills a card. (Each player puts the top card of their library into their graveyard.)

Koma's Faithful

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
When Koma's Faithful dies, each player mills three cards. (They each put the top three cards of their library into their graveyard.)

Summon Undead

You may mill three cards. Then return a creature card from your graveyard to the battlefield. (To mill a card, put the top card of your library into your graveyard.)

Carrier Thrall

When Carrier Thrall dies, create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this creature: Add {C}."

Sibsig Host

When Sibsig Host enters, each player mills three cards.

Vicious Rumors

Vicious Rumors deals 1 damage to each opponent. Each opponent discards a card, then mills a card. You gain 1 life.

Myr Moonvessel

Balustrade Spy

Flying
When Balustrade Spy enters, target player reveals cards from the top of their library until they reveal a land card, then puts those cards into their graveyard.

Returned Reveler

When Returned Reveler dies, each player mills three cards.

Cathodion

Desperate Bloodseeker

Lifelink
When Desperate Bloodseeker enters, target player mills two cards. (They put the top two cards of their library into their graveyard.)