msem-instigator

As Wayward Wanderers enters, you may have it become X/X with ward {X} and “Other creatures you control have base power and toughness X/X.”
{1}{G}: Return Wayward Wanderers to its owner's hand.

Trample, haste
When Weak-Spot Colossus is dealt exactly 1 damage, destroy it.

Bleed {2}{R} (You may cast this spell for its bleed cost if an opponent has lost life this turn.)
Target player loses 2 life. If this spell's bleed cost was paid, it deals 1 damage to each creature that player controls.

When Weald Sentry enters the battlefield, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
When Weald Sentry dies, draw a card.

When Weald Wanderer enters the battlefield, you gain 3 life and each opponent loses 2 life.
{1}, Pay 1 life: Shuffle Weald Wanderer into its owner's library. If you do, draw a card.

Create an 8/8 blue Kraken creature token.
{2}{U}, Discard Wealth of the Flood: Create a Treasure token. Scry 2.

Mill five cards, then return up to one permanent card from your graveyard to your hand.

When Wealthy Merchants enters the battlefield, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Destroy target artifact.
Cycling {1}{R} ({1}{R}, Discard this card: Draw a card.)

Until end of turn, target noncreature, non-Equipment artifact becomes an Equipment with equip X and “Equipped creature gets +X/+0”, where X is that artifact's mana value.

When Weary Adventurer enters the battlefield, return a permanent you control to its owner's hand.

Haste
Whenever Weary Sentinel attacks, you may pay {2}{R}{W}. If you do, it gets +2/+0 and gains first strike until end of turn.

Flash (You may cast this spell any time you could cast an instant.)
Defender
When Weary Steward enters the battlefield, prevent all combat damage target creature would deal this turn.

{2}{R}: Creatures you control get +1/+0 until end of turn.
{1}{G}: Creatures you control gain trample until end of turn.

Creatures you control get +0/+2 and gain hexproof until end of turn.

Weathered Fortress enters the battlefield tapped.
{T}: Add {U} or {R}.
{U}{R}: Until end of turn, Frozen Hinterlands becomes a 1/4 blue and red Golem creature with with “When this creature attacks, switch its power and toughness until end of turn” and “Whenever this creature attacks or blocks, torment yourself.” It's still a land. (To torment yourself, lose 3 life unless you discard a card or sacrifice a nonland permanent.)

Whenever Weathered Skiff attacks, it gets +1/+1 until end of turn.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Ship Vehicle becomes an artifact creature until end of turn.)

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
When Weathered Veteran dies, you may put a -1/-1 counter on target creature.

{T}, Pay 1 life: Add {U} or {B}.
{2}, {T}, Sacrifice Weathered Wharf and another permanent: Draw a card. Activate only during your turn.

Whenever Weave Etcher enters the battlefield or equipped creature attacks, create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”
Equip {1}

Reach
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)

Whenever Weaver of Lore attacks, you may reveal your hand. Weaver of Lore gets +2/+2 until end of turn if you reveal two or more blue cards this way.

When Weaver of Mists enters the battlefield, substantiate target card in your graveyard. (Put it onto the battlefield face down as a 2/2 creature. You may turn it face up and cast it at any time for its mana cost if it isn't a creature.)
Spells you cast from anywhere other than your hand cost {1} less to cast.

Whenever an enchantment enters the battlefield under your control, target opponent loses 1 life and you gain 1 life.

Vision (Whenever this or another creature enters the battlefield under your control, reveal the top card of your library. Then you may put that card into your graveyard.)
Whenever Weaver of the Winds envisions an instant or sorcery card, draw a card.