: Add .

Watchdog blocks each combat if able.
As long as Watchdog is untapped, all creatures attacking you get -1/-0.

All Sliver creatures get +0/+2.

Hideaway (This creature enters the battlefield tapped. When it does, look at the top four cards of your library, exile one face down, then put the rest on the bottom of your library.)
When Watcher for Tomorrow leaves the battlefield, put the exiled card into its owner's hand.

Flying
When Watcher in the Mist enters the battlefield, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Flying
Morph—Reveal a white card in your hand. (You may cast this card face down as a 2/2 creature for . Turn it face up any time for its morph cost.)
When Watcher of the Roost is turned face up, you gain 2 life.

Flying
Creature spells with flying you cast cost less to cast.
Whenever another creature with flying enters the battlefield under your control, Watcher of the Spheres gets +1/+1 until end of turn.

Exile Watchers of the Dead: Each opponent chooses two cards in their graveyard and exiles the rest.

: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

When Watchful Giant enters the battlefield, create a 1/1 white Human creature token.

Watchwing Scarecrow has vigilance as long as you control a white creature.
Watchwing Scarecrow has flying as long as you control a blue creature.

As Water Gun Balloon Game enters the battlefield, each player puts a pop! counter on "0."
Whenever a player casts a spell, move that player's pop! counter up one.
Whenever a player's pop! counter hits "5," that player creates a 5/5 pink Giant Teddy Bear creature token and resets all pop! counters to "0."

: Water Servant gets +1/-1 until end of turn.
: Water Servant gets -1/+1 until end of turn.

Water Wurm gets +0/+1 as long as an opponent controls an Island.

: Watercourser gets +1/-1 until end of turn.

, , Discard a card: Return target creature to its owner's hand.

Whenever a creature with flying enters the battlefield under your control, Waterkin Shaman gets +1/+1 until end of turn.

Enchant creature
When Waterknot enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

: Add . Spend this mana only to cast spells with watermarks.