Suffocating Fumes

Creatures your opponents control get -1/-1 until end of turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Thraben Inspector

When Thraben Inspector enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Eagles of the North

Flying
When Eagles of the North enters, creatures you control get +1/+0 and gain first strike until end of turn.
Plainscycling {1} ({1}, Discard this card: Search your library for a Plains card, reveal it, put it into your hand, then shuffle.)

Late to Dinner

Return target creature card from your graveyard to the battlefield. Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Archaeomancer

When Archaeomancer enters, return target instant or sorcery card from your graveyard to your hand.

Kor Skyfisher

Flying
When Kor Skyfisher enters, return a permanent you control to its owner's hand.

Rescue the Foal

Exile target creature you control, then return that card to the battlefield under its owner's control. (Then exile this card. You may cast the creature later from exile.)

Pegasus Guardian

Flying
At the beginning of your end step, if a permanent you controlled left the battlefield this turn, create a 1/1 white Pegasus creature token with flying.

Pegasus Guardian // Rescue the Foal

Dust to Dust

Plains

Soul of Migration

Flying
When Soul of Migration enters, create two 1/1 white Bird creature tokens with flying.
Evoke {3}{W} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Mulldrifter

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Lórien Revealed

Draw three cards.
Islandcycling {1} ({1}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Soul Warden

Whenever another creature enters, you gain 1 life.

Inspiring Overseer

Flying
When this creature enters, you gain 1 life and draw a card.

Sunlit Marsh

({T}: Add {W} or {B}.)
Sunlit Marsh enters tapped.

Dispel

Stonehorn Dignitary

When Stonehorn Dignitary enters, target opponent skips their next combat phase.

Man-o'-War

When Man-o'-War enters, return target creature to its owner's hand.

Counterspell

Azorius Chancery

Azorius Chancery enters tapped.
When Azorius Chancery enters, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Cast Down

Contaminated Aquifer

({T}: Add {U} or {B}.)
Contaminated Aquifer enters tapped.

Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

Island

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.

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Tranquil Cove

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {W} or {U}.