msem-instigator

Whenever an enchantment you control enters, target opponent loses 1 life and you gain 1 life.

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.

Flying
Welkin Tern can block only creatures with flying.

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.)

{T}: Add {C}.
{9}, {T}, Exile Whiterun Gates: Take an extra turn after this one.

{T}: Add {C}.
{T}: Each opponent may draw a card. For each player who does, draw a card.

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.”)

Target creature gains lifelink or winnow until end of turn. (Damage dealt to it also causes its controller to lose that much life.)
Put the bottom card of your library into your hand.

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.

Frenzy 1 (Whenever this creature attacks and isn't blocked, it gets +1/+0 until end of turn.)
Wild Haploc has first strike as long as it's attacking.

When Wild Hermit dies, create a 2/2 white Cat creature token.
Revive—{3}{G}{G}, Sacrifice a creature. ({3}{G}{G}, Sacrifice a creature, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.
Inscribe {2}{R}{R} ({2}{R}{R}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

Create three 1/1 red Goblin creature tokens.

{B}, {T}: Destroy target tapped creature.

{1}, Sacrifice another creature: Wildborn Swindler deals 1 damage to target player or planeswalker. Scry 1. (To scry 1, look at the top card of your library. You may put that card on the bottom of your library.)
{1}, Discard a card at random: Wildborn Swindler deals 1 damage to you. Draw a card.

Wildfire Elemental has frenzy 4 as long as you control no other creatures. (Whenever this creature attacks and isn't blocked, it gets +4/+0 until end of turn.)
Wildfire Elemental has frenzy 4 as long as you have no cards in hand.