Massacre Wurm

When this creature enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Ghostly Flicker

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

Displacer Kitten

Avoidance — Whenever you cast a noncreature spell, exile up to one target nonland permanent you control, then return that card to the battlefield under its owner's control.

Thassa, Deep-Dwelling

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature.
At the beginning of your end step, exile up to one other target creature you control, then return that card to the battlefield under your control.
{3}{U}: Tap another target creature.

Eternal Witness

When this creature enters, you may return target card from your graveyard to your hand.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Deadeye Navigator

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Deadeye Navigator is paired with another creature, each of those creatures has "{1}{U}: Exile this creature, then return it to the battlefield under your control."

Yarok, the Desecrated

Deathtouch, lifelink
If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Elvish Visionary

Peregrine Drake

Flying
When this creature enters, untap up to five lands.

Agent of Treachery

When this creature enters, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Spark Double

You may have this creature enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Farhaven Elf

When this creature enters, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Topiary Stomper

Vigilance (Attacking doesn't cause this creature to tap.)
When this creature enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
This creature can't attack or block unless you control seven or more lands.

Tireless Tracker

Landfall — Whenever a land you control enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you sacrifice a Clue, put a +1/+1 counter on this creature.

Guardian Project

Whenever a nontoken creature you control enters, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Baleful Strix

Flying, deathtouch
When this creature enters, draw a card.

Rampaging Baloths

Trample
Landfall — Whenever a land you control enters, create a 4/4 green Beast creature token.

Hostage Taker

When this creature enters, exile another target creature or artifact until this creature leaves the battlefield. You may cast that card for as long as it remains exiled, and mana of any type can be spent to cast that spell.

Aether Channeler

When this creature enters, choose one —
• Create a 1/1 white Bird creature token with flying.
• Return another target nonland permanent to its owner's hand.
• Draw a card.

Scute Swarm

Landfall — Whenever a land you control enters, create a 1/1 green Insect creature token. If you control six or more lands, create a token that's a copy of this creature instead.