Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
When Yavimaya Dryad enters the battlefield, you may search your library for a Forest card and put it onto the battlefield tapped under target player's control. If you do, shuffle your library.

Echo (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Yavimaya Granger enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle your library.

When Yavimaya Sapherd enters the battlefield, create a 1/1 green Saproling creature token.

When Yeva's Forcemage enters the battlefield, target creature gets +2/+2 until end of turn.

Companion — Your starting deck contains at least twenty cards more than the minimum deck size. (If this card is your chosen companion, you may put it into your hand from outside the game for any time you could cast a sorcery.)
Flying
When Yorion enters the battlefield, exile any number of other nonland permanents you own and control. Return those cards to the battlefield at the beginning of the next end step.

Yorvo, Lord of Garenbrig enters the battlefield with four +1/+1 counters on it.
Whenever another green creature enters the battlefield under your control, put a +1/+1 counter on Yorvo. Then if that creature's power is greater than Yorvo's power, put another +1/+1 counter on Yorvo.

When Yuki-Onna enters the battlefield, destroy target artifact.
Whenever you cast a Spirit or Arcane spell, you may return Yuki-Onna to its owner's hand.

Vigilance, reach, trample
When Zacama, Primal Calamity enters the battlefield, if you cast it, untap all lands you control.
: Zacama deals 3 damage to target creature.
: Destroy target artifact or enchantment.
: You gain 3 life.

: This turn, each creature you control enters the battlefield with an additional +1/+1 counter on it.
, Remove a +1/+1 counter from a creature you control: Draw a card.

Haste
When Zealous Conscripts enters the battlefield, gain control of target permanent until end of turn. Untap that permanent. It gains haste until end of turn.

When Zegana, Utopian Speaker enters the battlefield, if you control another creature with a +1/+1 counter on it, draw a card.
: Adapt 4. (If this creature has no +1/+1 counters on it, put four +1/+1 counters on it.)
Each creature you control with a +1/+1 counter on it has trample.

Riot (This creature enters the battlefield with your choice of a +1/+1 counter or haste.)

Partner with Okaun, Eye of Chaos (When this creature enters the battlefield, target player may put Okaun into their hand from their library, then shuffle.)
At the beginning of combat on your turn, flip a coin until you lose a flip.
Whenever a player wins a coin flip, draw a card.

Whenever a land enters the battlefield, Zo-Zu the Punisher deals 2 damage to that land's controller.

Amplify 1 (As this creature enters the battlefield, put a +1/+1 counter on it for each Zombie card you reveal in your hand.)
Trample

As Zombie Fanboy enters the battlefield, choose an artist.
Whenever a permanent with art by the chosen artist is put into a graveyard, put two +1/+1 counters on Zombie Fanboy.

Zombie Mob enters the battlefield with a +1/+1 counter on it for each creature card in your graveyard.
When Zombie Mob enters the battlefield, exile all creature cards from your graveyard.

Flash
When Zulaport Duelist enters the battlefield, up to one target creature gets -2/-0 until end of turn. Its controller mills two cards. (They put the top two cards of their library into their graveyard.)

Flying, deathtouch
When Zyym, Mesmeric Lord enters the battlefield, target opponent chooses an order for the cards in their hand, then reveals them one by one until you say stop. That player then discards the most recently revealed card.