Spotter Thopter

Prototype {3}{U} — 2/3 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
Flying
When Spotter Thopter enters, scry X, where X is its power.

Swift Spiral

Exile target nontoken creature. Return it to the battlefield under its owner's control at the beginning of the next end step.

Twining Twins

Twining Twins // Swift Spiral

Cave of the Frost Dragon

If you control two or more other lands, Cave of the Frost Dragon enters tapped.
{T}: Add {W}.
{4}{W}: Cave of the Frost Dragon becomes a 3/4 white Dragon creature with flying until end of turn. It's still a land.

Island

Port Town

As Port Town enters, you may reveal a Plains or Island card from your hand. If you don't, Port Town enters tapped.
{T}: Add {W} or {U}.

Elder Deep-Fiend

Flash
Emerge {5}{U}{U} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.)
When you cast this spell, tap up to four target permanents.

Planar Incision

Exile target artifact or creature, then return it to the battlefield under its owner's control with a +1/+1 counter on it.

Arcane Proxy

Prototype {1}{U}{U} — 2/1 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
When Arcane Proxy enters, if you cast it, exile target instant or sorcery card with mana value less than or equal to Arcane Proxy's power from your graveyard. Copy that card. You may cast the copy without paying its mana cost.

Autonomous Assembler

Prototype {1}{W} — 2/2 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
Vigilance
{1}, {T}: Put a +1/+1 counter on target Assembly-Worker you control.

Prairie Stream

({T}: Add {W} or {U}.)
Prairie Stream enters tapped unless you control two or more basic lands.

Circuit Mender

When Circuit Mender enters, you gain 2 life.
When Circuit Mender leaves the battlefield, draw a card.

Fateful Absence

Destroy target creature or planeswalker. Its controller investigates. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Plains

Dawnbringer Cleric

When Dawnbringer Cleric enters, choose one —
• Cure Wounds — You gain 2 life.
• Dispel Magic — Destroy target enchantment.
• Gentle Repose — Exile target card from a graveyard.

Combat Thresher

Prototype {2}{W} — 1/1 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
Double strike
When Combat Thresher enters, draw a card.

Touch the Spirit Realm

When Touch the Spirit Realm enters, exile up to one target artifact or creature until Touch the Spirit Realm leaves the battlefield.
Channel — {1}{W}, Discard Touch the Spirit Realm: Exile target artifact or creature. Return it to the battlefield under its owner's control at the beginning of the next end step.