Insidious Dreams

As an additional cost to cast this spell, discard X cards.
Search your library for X cards, then shuffle and put those cards on top in any order.

Cinder Shade

{B}: Cinder Shade gets +1/+1 until end of turn.
{R}, Sacrifice Cinder Shade: It deals damage equal to its power to target creature.

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

Dragon Mask

{3}, {T}: Target creature you control gets +2/+2 until end of turn. Return it to its owner's hand at the beginning of the next end step. (Return it only if it's on the battlefield.)

Skeletal Scrying

As an additional cost to cast this spell, exile X cards from your graveyard.
You draw X cards and you lose X life.

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. Sulfurous Springs deals 1 damage to you.

Duress

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

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Tainted Peak

{T}: Add {C}.
{T}: Add {B} or {R}. Activate only if you control a Swamp.

Crypt Rats

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

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.)

Swamp

Dragon Engine

{2}: Dragon Engine gets +1/+0 until end of turn.

Dread of Night

Lightning Rift

Whenever a player cycles a card, you may pay {1}. If you do, Lightning Rift deals 2 damage to any target.

Bloodstone Cameo

Leshrac's Rite

Enchant creature
Enchanted creature has swampwalk. (It can't be blocked as long as defending player controls a Swamp.)

Spawning Pool

Spawning Pool enters tapped.
{T}: Add {B}.
{1}{B}: Spawning Pool becomes a 1/1 black Skeleton creature with "{B}: Regenerate this creature" until end of turn. It's still a land. (If it regenerates, the next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Pyromania

{1}{R}, Discard a card at random: Pyromania deals 1 damage to any target.
{1}{R}, Sacrifice Pyromania: It deals 1 damage to any target.

Lightning Dart

Lightning Dart deals 1 damage to target creature. If that creature is white or blue, Lightning Dart deals 4 damage to it instead.

Blazing Specter

Flying, haste
Whenever Blazing Specter deals combat damage to a player, that player discards a card.

Urborg Volcano

Urborg Volcano enters tapped.
{T}: Add {B} or {R}.

Cabal Torturer

{B}, {T}: Target creature gets -1/-1 until end of turn.
Threshold — {3}{B}{B}, {T}: Target creature gets -2/-2 until end of turn. Activate only if seven or more cards are in your graveyard.

Unhinge

Target player discards a card.
Draw a card.

Earthquake

Earthquake deals X damage to each creature without flying and each player.

Shadowblood Ridge

Backlash

Tap target untapped creature. That creature deals damage equal to its power to its controller.

Nantuko Shade

{B}: Nantuko Shade gets +1/+1 until end of turn.

Greed

Mountain

Grand Coliseum

Grand Coliseum enters tapped.
{T}: Add {C}.
{T}: Add one mana of any color. Grand Coliseum deals 1 damage to you.

Mind Burst

Target player discards X cards, where X is one plus the number of cards named Mind Burst in all graveyards.

Millikin

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)