Peregrine Drake

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

Ayara, First of Locthwain

Whenever Ayara, First of Locthwain or another black creature you control enters, each opponent loses 1 life and you gain 1 life.
{T}, Sacrifice another black creature: Draw a card.

Dire Undercurrents

Whenever a blue creature you control enters, you may have target player draw a card.
Whenever a black creature you control enters, you may have target player discard a card.

Mnemonic Wall

Defender
When Mnemonic Wall enters, you may return target instant or sorcery card from your graveyard to your hand.

Wasteland Strangler

Devoid (This card has no color.)
When Wasteland Strangler enters, you may put a card an opponent owns from exile into that player's graveyard. If you do, target creature gets -3/-3 until end of turn.

Oona's Blackguard

Flying
Each other Rogue creature you control enters with an additional +1/+1 counter on it.
Whenever a creature you control with a +1/+1 counter on it deals combat damage to a player, that player discards a card.

Oona, Queen of the Fae

Flying
{X}{U/B}: Choose a color. Target opponent exiles the top X cards of their library. For each card of the chosen color exiled this way, create a 1/1 blue and black Faerie Rogue creature token with flying.

Orc Sureshot

Whenever another creature you control enters, target creature an opponent controls gets -1/-1 until end of turn.

Illusionist's Stratagem

Exile up to two target creatures you control, then return those cards to the battlefield under their owner's control.
Draw a card.

Possessed Skaab

When Possessed Skaab enters, return target instant, sorcery, or creature card from your graveyard to your hand.
If Possessed Skaab would die, exile it instead.

Displace

Exile up to two target creatures you control, then return those cards to the battlefield under their owner's control.

Ghostly Flicker

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

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Ulamog's Nullifier

Devoid (This card has no color.)
Flash
Flying
When Ulamog's Nullifier enters, you may put two cards your opponents own from exile into their owners' graveyards. If you do, counter target spell.

Naru Meha, Master Wizard

Flash
When Naru Meha, Master Wizard enters, copy target instant or sorcery spell you control. You may choose new targets for the copy.
Other Wizards you control get +1/+1.

Archaeomancer

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

Scion of Oona

Flash
Flying
Other Faerie creatures you control get +1/+1.
Other Faeries you control have shroud. (They can't be the targets of spells or abilities.)

Scheming Symmetry

Choose two target players. Each of them searches their library for a card, then shuffles and puts that card on top.