Altar of the Brood

Whenever another permanent you control enters, each opponent mills a card.

Snow-Covered Island

Retreat to Coralhelm

Landfall — Whenever a land you control enters, choose one —
• You may tap or untap target creature.
• Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Staff of Domination

{1}: Untap Staff of Domination.
{2}, {T}: You gain 1 life.
{3}, {T}: Untap target creature.
{4}, {T}: Tap target creature.
{5}, {T}: Draw a card.

Walking Ballista

Walking Ballista enters with X +1/+1 counters on it.
{4}: Put a +1/+1 counter on Walking Ballista.
Remove a +1/+1 counter from Walking Ballista: It deals 1 damage to any target.

Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Walking Atlas

{T}: You may put a land card from your hand onto the battlefield.

Meloku the Clouded Mirror

Flying
{1}, Return a land you control to its owner's hand: Create a 1/1 blue Illusion creature token with flying.

Thassa's Oracle

When Thassa's Oracle enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Soratami Cloudskater

Flying
{2}, Return a land you control to its owner's hand: Draw a card, then discard a card.

Pili-Pala

Flying
{2}, {Q}: Add one mana of any color. ({Q} is the untap symbol.)

Emergence Zone

{T}: Add {C}.
{1}, {T}, Sacrifice Emergence Zone: You may cast spells this turn as though they had flash.

Crashing Drawbridge

Defender
{T}: Creatures you control gain haste until end of turn.

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

Grand Architect

Other blue creatures you control get +1/+1.
{U}: Target artifact creature becomes blue until end of turn.
Tap an untapped blue creature you control: Add {C}{C}. Spend this mana only to cast artifact spells or activate abilities of artifacts.

Soratami Savant

Flying
{3}, Return a land you control to its owner's hand: Counter target spell unless its controller pays {3}.

Harbinger of the Seas

Oboro Breezecaller

Flying
{2}, Return a land you control to its owner's hand: Untap target land.

Extraplanar Lens

Imprint — When Extraplanar Lens enters, you may exile target land you control.
Whenever a land with the same name as the exiled card is tapped for mana, its controller adds one mana of any type that land produced.