msem-instigator

When Woopip Sproutling enters, germinate. (Put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

Flash
When Wormwood's Agent dies, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Vigilance
When Worn Peacekeeper dies, create a 1/1 white Soldier creature token with vigilance.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
When Worried Vulpine has three or more +1/+1 counters on it, remove them all and transform it.

Ferocious — At the beginning of each combat, if you control a creature with power 4 or greater, Worshipper Whelp gets +2/+0 until end of turn.

Ferocious — Whenever a creature with power 4 or greater you control enters, untap all lands you control.

Reach
{T}: Yangzhi Cloudpiercer deals 1 damage to target player or planeswalker.

Menace
Yaran's Enforcer gets +1/+1 as long as you foretold a card this turn.
Yaran's Enforcer gets +1/+1 as long as you cast a foretold spell this turn.

When Young Chasqui enters, 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.

Wanderlust — Whenever a land you control enters, if you control four or more differently named lands, create a 1/1 green Saproling creature token.

Whenever you cast an instant or sorcery spell, tap target creature an opponent controls.

Whenever a nontoken creature you control dies, create a 1/1 black Skeleton creature token.

Whenever you cast a cryptic spell, create a 1/1 white Human creature token with lifelink. (Artifacts, enchantments, and modal spells are cryptic.)

Whenever Yri, the Daring Blade and exactly one other creature attack, Yri and that creature can't be blocked by creatures with mana value 3 or less this turn.

Flying
When Yujei enters, create a 1/1 white Bird creature token with flying.
{2}{W}: Put a +1/+1 counter on another target creature. It gains flying until end of turn. If it already has flying, put a +1/+1 counter on Yujei instead.

{2}{B}, Sacrifice a Clue: Target creature gets -3/-3 until end of turn.

{T}: Add {C}.
{T}, Sacrifice a creature: Add one mana of any color.

Trample
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Zealous Rabble gets +1/+1 for each creature token you control.
At the beginning of your end step, if you're horrific, create a token that's a copy of Zealous Rabble, except it doesn't have this ability. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{G}: Zen Ascendant becomes a copy of a creature token you control until end of turn. (It's not a token.)

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
{T}: Add {G}.

When Zhedina Envoys leaves the battlefield, create two 1/1 Scout creature tokens that are all colors.

When Zhedina Valiant enters, 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.”

Menace
Ferocious — Whenever Zhenya, the Draconic becomes blocked by a creature, it deals 3 damage to that creature if you control a creature with power 4 or greater.