msem-instigator

Flying (This creature can't be blocked except by creatures with flying or reach.)
Vigilance (Attacking doesn't cause this creature to tap.)

When Wavebreaker enters, add two mana of any one color. You can't spend this mana to cast spells.

Create two Idol tokens, then counter target spell unless its controller pays {1} for each Idol you control. (They're artifacts with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

At the beginning of your upkeep, each player draws a card.

When Wayfaring Swindler enters, destroy all permanents attached to target creature.

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.

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.

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

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

Weathered Fortress enters tapped.
{T}: Add {U} or {R}.
{U}{R}: Until end of turn, Weathered Fortress 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.)

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.

This spell costs {1} less to cast for each creature you control that attacked this turn.
First strike
Whenever Weavetide Militia and at least one other creature attack, creatures you control get +1/+0 until end of turn.

Well of Eternity enters with X charge counters on it.
At the beginning of your first main phase, choose a color, then add one mana of that color for each charge counter on Well of Eternity.

This spell can't be countered.
If a spell or ability an opponent controls causes you to sacrifice Wellspring of Creation, you may put it on the top or bottom of its owner's library instead of putting it into that player's graveyard.

Whim of Ifram deals 4 damage to target creature chosen at random.

Flying, prowess
{U}{R}, Exile an instant or sorcery card from your graveyard: Whimsical Elemental gets +1/+1 until end of turn.

Prowess, haste
Mirage {R} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Whenever Whitepeak Channeler deals combat damage to a creature, tap that creature. That creature doesn't untap during its controller's next untap step.

Vigilance

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)

When Whiterun Ordainer enters, you gain 4 life.

Each opponent sacrifices a creature. For each creature sacrificed this way, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

Gain control of target land.

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.)
When Wild Gravetender enters, you gain 2 life for each creature card in your graveyard.
{1}{G}, Sacrifice a creature: Return Wild Gravetender from your graveyard to your hand.