Avenger of Zendikar

When this creature enters, create a 0/1 green Plant creature token for each land you control.
Landfall — Whenever a land you control enters, you may put a +1/+1 counter on each Plant creature you control.

Spitting Image

Create a token that's a copy of target creature.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Cackling Counterpart

Create a token that's a copy of target creature you control.
Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Biovisionary

At the beginning of the end step, if you control four or more creatures named Biovisionary, you win the game.

Tajuru Warcaller

Rally — Whenever this creature or another Ally you control enters, creatures you control get +2/+2 until end of turn.

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.

Kalastria Healer

Rally — Whenever this creature or another Ally you control enters, each opponent loses 1 life and you gain 1 life.

Halimar Excavator

Whenever this creature or another Ally you control enters, target player mills X cards, where X is the number of Allies you control.

Nylea's Colossus

Constellation — Whenever this creature or another enchantment you control enters, double target creature's power and toughness until end of turn.

Hagra Diabolist

Whenever this creature or another Ally you control enters, you may have target player lose life equal to the number of Allies you control.

Moritte of the Frost

Changeling (This card is every creature type.)
You may have Moritte enter as a copy of a permanent you control, except it's legendary and snow in addition to its other types and, if it's a creature, it enters with two additional +1/+1 counters on it and has changeling.

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Turntimber Ranger

Whenever this creature or another Ally you control enters, you may create a 2/2 green Wolf creature token. If you do, put a +1/+1 counter on this creature.

Doomwake Giant

Constellation — Whenever this creature or another enchantment you control enters, creatures your opponents control get -1/-1 until end of turn.

Gray Merchant of Asphodel

When this creature enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Clone

You may have this creature enter as a copy of any creature on the battlefield.

Merchant Raiders

Whenever this creature or another Pirate you control enters, tap up to one target creature. That creature doesn't untap during its controller's untap step for as long as you control this creature.

Progenitor Mimic

You may have this creature enter as a copy of any creature on the battlefield, except it has "At the beginning of your upkeep, if this creature isn't a token, create a token that's a copy of this creature."