Cast Down

Contaminated Aquifer

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

Crypt Rats

{X}: Crypt Rats deals X damage to each creature and each player. Spend only black mana on X.

Recoil

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

Dark Ritual

Rancid Earth

Destroy target land.
Threshold — If seven or more cards are in your graveyard, instead destroy that land and Rancid Earth deals 1 damage to each creature and each player.

Choking Sands

Destroy target non-Swamp land. If that land was nonbasic, Choking Sands deals 2 damage to the land's controller.

Fade Away

For each creature, its controller sacrifices a permanent of their choice unless they pay {1}.

Chainer's Edict

Target player sacrifices a creature of their choice.
Flashback {5}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Icequake

Destroy target land. If that land was a snow land, Icequake deals 1 damage to that land's controller.

Troll of Khazad-dûm

Troll of Khazad-dûm can't be blocked except by three or more creatures.
Swampcycling {1} ({1}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Island

Thorn of the Black Rose

Deathtouch
When Thorn of the Black Rose enters, you become the monarch.

Exhume

Each player puts a creature card from their graveyard onto the battlefield.

Peat Bog

Peat Bog enters tapped with two depletion counters on it.
{T}, Remove a depletion counter from Peat Bog: Add {B}{B}. If there are no depletion counters on Peat Bog, sacrifice it.

Obscura Storefront

When Obscura Storefront enters, sacrifice it. When you do, search your library for a basic Plains, Island, or Swamp card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

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.)

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)