msem-instigator

When Woopip Wanderer enters the battlefield, create two colorless artifact tokens named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”
{2}{G}: Germinate. (Put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

When Worship of the Sun enters the battlefield, draw a card, then choose a card name.
At the beginning of your upkeep, you may tap three untapped creatures you control. If you do, search your library for an enchantment card with the chosen name, put it onto the battlefield, then shuffle.

Haste
When Wretched Merfolk enters the battlefield, target creature can't block this turn.

When Wretched Spawn enters the battlefield, you may return target permanent to its owner's hand. If you do, that player discards a card.
Unearth {4}{U}{B} ({4}{U}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

When Writhing Gateway enters the battlefield, you may discard a card. If you do, create a 5/3 black Horror creature token.
{1}{B}{B}, Discard a card: Create a 5/3 black Horror creature token.

When Wu, the Shackled enters the battlefield, you may have an opponent gain control of it. If you do, draw two cards.
At the beginning of your upkeep, if you don't own Wu, she fights another target creature you control and its owner draws a card.

(Choose only one work as a sorcery to add its ability.)
When Xie'e Amphitheatre enters the battlefield, search your library for a card and exile it face down, then shuffle. You may cast that card on any turn you sacrificed a permanent.
{B}: Intro: Together
At the beginning of your upkeep, you lose 1 life and create a 0/1 black Cultist creature token with “{1}{B}{B}, Sacrifice three Cultists: Create a 5/5 black Demon creature token.”
{2}{B}: Finale: Alone
Whenever a Demon enters the battlefield under your control, each opponent loses life equal to its power and you gain that much life.

Flash
This spell can't be countered.
When Xing, the Lucky Charm enters the battlefield, draw three cards.
{U}{R}, Discard three cards: Return Xing from your graveyard to your hand.

When Yamisaran Bladedancer enters the battlefield, you may attach an Equipment you control to target creature you control.

When Yamisaran Guard enters the battlefield, create a colorless Equipment artifact token with “Equipped creature gets +1/+1” and equip {1}.

Enchant creature
When Yenzu Puppeteering enters the battlefield, draw a card.
{1}{U}: Untap enchanted creature.

When Young Chasqui enters the battlefield, if you cast it, reveal the top five cards of your library. Put any number of creatures named Young Chasqui from among them into your hand. Put the rest of the revealed cards on the bottom of your library in a random order.
A deck can have any number of cards named Young Chasqui.

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Young Tempter enters the battlefield, you draw a card and you lose 1 life.

Other Rebel creatures you control get +1/+0.
When Youthful Renegade enters the battlefield, create a 1/1 white Rebel creature token.

When Yron Bay Sentinel enters the battlefield, draw a card.

When Zareen, the Second Shah enters the battlefield, search your library for a creature card with mana value 2 or less or a planeswalker card, reveal it, put it into your hand, then shuffle.
Monument {2}{W}{W} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

Flying
When Zenith of Greed enters the battlefield, search your library for up to two cards named Treasure Hoard and put them onto the battlefield, then shuffle.

Flying
When Zephyr Gliders enters the battlefield, up to two target creatures you control gain flying until end of turn.

First strike (This creature deals combat damage before creatures without first strike.)
When Zephyr Rider enters the battlefield, you may have another target creature you control gain first strike until end of turn.

First strike, menace
When Zhargetan Reclaimer enters the battlefield, put any number of cards your opponents own from exile into their owners' graveyards. If three or more cards were put into graveyards this way, create two 1/1 Scout creature tokens that are all colors.

Flash
When Zhedina Coastguard enters the battlefield, you may have any number of creatures you control have base power and toughness 1/3, 2/2, or 3/1 until end of turn.

When Zhedina Exchange enters the battlefield, choose a basic land type.
Basic lands you control of the chosen type have “{T}: Add one mana of any color.”
{T}: Add {C}.

When Zhedina Provisioner enters the battlefield, creatures you control get +1/+1 until end of turn. You gain 2 life.

When Zhedina Valiant enters the battlefield, create a white and blue Aura enchantment token named Winds of Chance attached to target creature. The token has enchant creature and “Enchanted creature gets +1/+0 and has flying and lifelink.”

Lifelink
When Zhehan, the Mediator enters the battlefield, you may put an Aura card with mana value 3 or less from your hand onto the battlefield attached to a creature it could enchant.