Defender
When Wall of Blossoms enters, draw a card.

Defender
When Wall of Heroes enters, tap target creature you don't control. That creature doesn't untap during its controller's next untap step.

Defender
When Wall of Mysteries enters, draw a card.

When this Rift enters or is traversed, look at the top three cards of your library. You may reveal a creature or land card and put it into your hand. Put the rest on the bottom of your library in a random order.
Traverse 2

War-Clan Dowager gets +1/+1 as long as you control another Centaur.

Create two 1/1 white Warrior creature tokens.

Flash
Flying
If an effect an opponent controls would cause them to take an extra turn, you take an extra turn instead.
{G}{U}: Return a creature you control to its owner's hand. Activate this ability only once each turn.

Target creature gets +4/-2 until end of turn.

Whenever you surveil, you may have Watcher's Roost become a 3/3 Bird creature with flying until end of turn.
{2}{U}: Surveil 1.

Once each turn, when you cast an instant or sorcery spell, you may create a 1/0 blue Elemental creature token.
Elementals you control get +1/+1.
{2}{U}, Sacrifice an Elemental: Tap up to one target creature. Scry 1.

When Wayward Drek enters, create a 1/1 colorless Cyborg artifact creature token.
Cybersoul {3}{W/B}

Reveal the top three cards of your library. You may put a creature, enchantment, or land card from among them into your hand and the rest on the bottom of your library in any order.

Whenever another nontoken creature you control enters, you may pay {1}. If you do, create a white Subroutine enchantment token named ALARM with “Whenever this Subroutine runs, create a 1/1 white Citizen creature token.”

When Weedy Wanderer leaves the battlefield or phases out, put a +1/+1 counter on a creature you control.

{3}{W}{U}: Tap target creature. You gain 2 life.

Return target creature to its owner's hand. If you controlled that creature, draw a card.

Destroy target tapped creature.

When Whisperlit Meditation enters, put a +1/+1 counter on each of up to two target creatures.
{1}{W}, Sacrifice Whisperlit Meditation: Tap up to two target creatures.

When White Spy enters, create a first strike Gadget, then attach it to White Spy.
Enchanted creatures and equipped creatures you control have hexproof from black.

Whenever a creature entering the battlefield under your control causes an ability of a permanent you control to trigger, draw a card. This ability triggers only once each turn.

Create X 1/1 white Insect creature tokens with flying.
Flashback—{3}{W}{W}, Tap X untapped creatures you control.

{2}, Sacrifice Wicked Fossil: Target player loses 2 life and you gain 2 life.
{2}{B}{B}: Return Wicked Fossil from your graveyard to the battlefield transformed. Activate only during your turn.

This creature gets +1/+1 for each card with a cycling ability in your graveyard.
Cycling {2}

Multitude {4}{G}{G}
Whenever a token you control enters, put a +1/+1 counter on Wildcourt Conserver.

Multitude {4}{W}
{W}, {T}: Put a +1/+1 counter on another target creature.