Archaeomancer

When Archaeomancer enters, return target instant or sorcery card from your graveyard to your hand.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Mystic Sanctuary

({T}: Add {U}.)
Mystic Sanctuary enters tapped unless you control three or more other Islands.
When Mystic Sanctuary enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Enlightened Tutor

Search your library for an artifact or enchantment card, reveal it, then shuffle and put that card on top.

Soulherder

Whenever a creature is exiled from the battlefield, put a +1/+1 counter on Soulherder.
At the beginning of your end step, you may exile another target creature you control, then return that card to the battlefield under its owner's control.

Corpse Knight

Whenever another creature you control enters, each opponent loses 1 life.

Cloudshift

Exile target creature you control, then return that card to the battlefield under your control.

Shrieking Drake

Flying
When Shrieking Drake enters, return a creature you control to its owner's hand.

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Genesis Chamber

Whenever a nontoken creature enters, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

Peregrine Drake

Flying
When Peregrine Drake enters, untap up to five lands.

Ghostly Flicker

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

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.)

Merchant Scroll

Search your library for a blue instant card, reveal that card, put it into your hand, then shuffle.