msem-instigator

Flying
When Windrider Elemental enters, target creature gains flying until end of turn.

Armed — Winterborn Savage gets +1/+1 and has vigilance as long as it's equipped.

Flash
When Wiretapper enters, choose one —
• Exile target spell. For as long as that card remains exiled, its owner may play it. A spell cast this way costs {2} more to cast.
• Create a copy of the card with target spell's name. You may cast the copy. (You still pay its costs.)

When Wise Farseer Chini enters, create a tapped colorless land token named Far-Off Lands with “{T}: Add one mana of any color.”

This spell costs {1} less to cast if you have more life than an opponent and {1} less to cast if you control a Cleric.
Deathtouch

Trample
{5}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)

When Woopip Wanderer enters, 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.)

Whenever an artifact you control enters or is put into a graveyard from the battlefield, Workshop Engineer gets +1/+1 until end of turn.

{T}, Sacrifice Worldshaper Adept: Choose two basic land types. Create a tapped colorless land token of the chosen types.

Wraith of the Fens gets +2/+2 as long as you've gained life this turn.

Flying
Assault {2}{B} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Wretched Lammasu assaults, each opponent discards a card.

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

Renown 2 (When this creature deals combat damage to a player, if it isn't renowned, put two +1/+1 counters on it and it becomes renowned.)
Each creature you control with a +1/+1 counter on it has indestructible.

Whenever one or more creatures you control deal combat damage to a player or planeswalker, put a +1/+1 counter on target creature you control.

Menace
Whenever a land enters, you may search its controller's library for up to three land cards with the same name as that card, put them into that player's graveyard, then that player shuffles.

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{4}{G}: Target creature gets +2/+2 until end of turn.

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

Other enchantment creatures you control get +1/+1.
As long as you control three or more enchantment creatures, if a triggered ability of an enchantment you control would trigger, that ability triggers an additional time.

{2}, Exile a land card from your graveyard: Create a token that's a copy of that land.

Flying
When Yielder of Ambition enters, target creature gets +2/+2 until end of turn.
Fleeting {W} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

Young Dragonheart gets +1/+0 and has first strike as long as you control a legendary creature.

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

Vigilance
Art of war — At the beginning of your end step, if Yuso, Light of Jidai dealt damage to an opponent this turn, you may search your library for a creature card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

Lifelink
Whenever Zagos Abomination attacks, exile another target creature you control, then return it to the battlefield under your control tapped and attacking. It gains menace until end of turn.

Whenever Zana, the Dreamer attacks, you may pay {3}{R}{R}. If you do, for each attacking nontoken creature you control, create a tapped and attacking token that's a copy of it, except the tokens aren't legendary. Exile those tokens at the beginning of the end step.