msem-instigator

Whenever you attack, create an X/X red Elemental creature token that's tapped and attacking, where X is the number of attacking creatures.
Fleeting {1}{R} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

When Vile Progenitor enters, create a 3/2 colorless Horror creature token.
As long as you control five or more lands, Horrors you control get +1/+1 and have trample.
Evoke {1}{G} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Deathtouch
When Vision Beyond the Waters enters, each player sacrifices two creatures other than this creature.

Target player mills a card. Create a 3/2 colorless Horror creature token. Put a decayed counter on it. (It can't block. When it attacks, sacrifice it at end of combat.)

Whenever you cast your second spell each turn, create a 1/1 blue Jellyfish Spirit creature token with flying.

Whenever Voracious Spawn enters or attacks, exile up to one target card from a graveyard. If you exile a permanent card, put a +1/+1 counter on Voracious Spawn. If you exile a nonpermanent card, you gain 1 life.

Defender
Whenever one or more creatures you control deal combat damage to a player, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
When Wall of Notes dies, draw a card.

At the beginning of combat on each opponent's turn, that player may exile a card from their graveyard and pay {2}. If the player doesn't, creatures they control can't attack you or planeswalkers you control this turn.

You may have Warped Physiognomist enter as a copy of any creature on the battlefield with mana value 3 or less.

When Warping Relic enters or is put into a graveyard from the battlefield, choose one —
• Draw two cards, then discard a card.
• Return another target nonland permanent to its owner's hand.
• Choose any number of target creatures. Switch their power and toughness until end of turn.

Trample, prowess
You may exert Wartorn Veteran as it attacks. When you do, double its power until end of turn. (An exerted creature won't untap during your next untap step.)

Wary Rider has first strike as long as its attacking.
Wary Rider gets +1/+0 as long as you control two or more other creatures.

{T}, Exert Weary Border Guard: Tap target creature. (An exerted creature won't untap during your next untap step.)

Whenever Weathered Storm enters or you cast your second spell each turn, Weathered Storm deals 3 damage to any target.

Choose any number —
• Each player loses X life.
• Each player discards X cards.
• Each player sacrifices X creatures.
• Each player sacrifices X lands.

You may cast What Remains of Samuel Quinn from your graveyard and from the battlefield. It costs {G}{G} more to cast this way.
What Remains of Samuel Quinn enters with your choice of X counters from among +1/+1, vigilance, reach, and trample.

Flash
Whenever Whimsical Dancer enters or is exerted, target creature gets +1/+0 and gains first strike until end of turn.
You may exert Whimsical Dancer as it attacks. (An exerted creature won't untap during your next untap step.)

Improve {1} ({1}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Other creatures you control have improve {1}.

You may exert Wiedfree Behemoth as it attacks. When you do, it gets +3/+3 and gains trample until end of turn. (An exerted creature won't untap during your next untap step.)

You may exert Wiedfree Berserker as it attacks. When you do, target creature can't block this turn. (An exerted creature won't untap during your next untap step.)
If exerting a creature you control causes a triggered ability of a permanent you control to trigger, that ability triggers another time.

When Wiedfree Investigator enters, return up to one target artifact card with mana value 2 or less from your graveyard to the battlefield.
{2}, Sacrifice an artifact: Draw a card.

Whenever a player casts an instant or sorcery spell, Wiedfree Roughrider deals 2 damage to that player.
Whenever Wiedfree Roughrider attacks, you may pay {X}. When you do, destroy target noncreature, nonland permanent with mana value X.

Voracious 1 (As this enters, you may sacrifice an artifact or creature. If you do, it enters with a +1/+1 counter on it.)
Vigilance, reach

If a permanent you control with mana value 5 or greater entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Enchant creature
Enchanted creature gets +1/+0 for each card type among cards in your graveyard and has menace.
Fleeting {B} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)