Man-o'-War

When Man-o'-War enters, return target creature to its owner's hand.

Island

Burglar Rat

When this creature enters, each opponent discards a card.

Faerie Seer

Flying
When Faerie Seer enters, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Cast Down

Phyrexian Rager

When Phyrexian Rager enters, you draw a card and you lose 1 life.

Mulldrifter

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Swamp

Echoing Decay

Target creature and all other creatures with the same name as that creature get -2/-2 until end of turn.

Sea Gate Oracle

When Sea Gate Oracle enters, look at the top two cards of your library. Put one of them into your hand and the other on the bottom of your library.

Counterspell

Vapor Snag

Return target creature to its owner's hand. Its controller loses 1 life.

Wretched Gryff

Emerge {5}{U} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.)
When you cast this spell, draw a card.
Flying

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Intervene

Counter target spell that targets a creature.

Thorn of the Black Rose

Deathtouch
When Thorn of the Black Rose enters, you become the monarch.

Wormfang Drake

Flying
When Wormfang Drake enters, sacrifice it unless you exile a creature you control other than Wormfang Drake.
When Wormfang Drake leaves the battlefield, return the exiled card to the battlefield under its owner's control.