Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate Nightscape Familiar.

Island

Stormscape Familiar

Flying
White spells and black spells you cast cost {1} less to cast.

Flooded Strand

{T}, Pay 1 life, Sacrifice Flooded Strand: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Plains

Meddling Mage

As Meddling Mage enters, choose a nonland card name.
Spells with the chosen name can't be cast.

Ravenous Rats

When Ravenous Rats enters, target opponent discards a card.

Recoil

Return target permanent to its owner's hand. Then that player discards a card.

Swamp

Mesmeric Fiend

When Mesmeric Fiend enters, target opponent reveals their hand and you choose a nonland card from it. Exile that card.
When Mesmeric Fiend leaves the battlefield, return the exiled card to its owner's hand.

Faceless Butcher

When Faceless Butcher enters, exile another target creature.
When Faceless Butcher leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Doomsday Specter

Flying
When Doomsday Specter enters, return a blue or black creature you control to its owner's hand.
Whenever Doomsday Specter deals combat damage to a player, look at that player's hand and choose a card from it. The player discards that card.

Duress

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Thought Devourer

Flying
Your maximum hand size is reduced by four.

Cabal Therapy

Choose a nonland card name. Target player reveals their hand and discards all cards with that name.
Flashback—Sacrifice a creature. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Mox Diamond

If Mox Diamond would enter, you may discard a land card instead. If you do, put Mox Diamond onto the battlefield. If you don't, put it into its owner's graveyard.
{T}: Add one mana of any color.

Polluted Delta

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.