Foreboding Ruins

As Foreboding Ruins enters the battlefield, you may reveal a Swamp or Mountain card from your hand. If you don't, Foreboding Ruins enters the battlefield tapped.
{T}: Add {B} or {R}.

Theater of Horrors

At the beginning of your upkeep, exile the top card of your library.
During your turn, if an opponent lost life this turn, you may play lands and cast spells from among cards exiled with Theater of Horrors.
{3}{R}: Theater of Horrors deals 1 damage to target opponent or planeswalker.

Smoldering Marsh

({T}: Add {B} or {R}.)
Smoldering Marsh enters the battlefield tapped unless you control two or more basic lands.

Spawn of Mayhem

Spectacle {1}{B}{B} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Flying, trample
At the beginning of your upkeep, Spawn of Mayhem deals 1 damage to each player. Then if you have 10 or less life, put a +1/+1 counter on Spawn of Mayhem.

Geothermal Bog

({T}: Add {B} or {R}.)
Geothermal Bog enters the battlefield tapped.

Gutterbones

Gutterbones enters the battlefield tapped.
{1}{B}: Return Gutterbones from your graveyard to your hand. Activate only during your turn and only if an opponent lost life this turn.

Footlight Fiend

When Footlight Fiend dies, it deals 1 damage to any target.

Swamp

Carnage

Carnage deals 3 damage to target opponent. That player discards two cards.

Carnival

Carnival deals 1 damage to target creature or planeswalker and 1 damage to that permanent's controller.

Carnival // Carnage

Light Up the Stage

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Bedazzle

Destroy target nonbasic land. Bedazzle deals 2 damage to target opponent or planeswalker.

Bedeck

Target creature gets +3/-3 until end of turn.

Bedeck // Bedazzle

Abrade

Choose one —
• Abrade deals 3 damage to target creature.
• Destroy target artifact.

Mountain

Judith, the Scourge Diva

Other creatures you control get +1/+0.
Whenever a nontoken creature you control dies, Judith, the Scourge Diva deals 1 damage to any target.

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Skewer the Critics

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Skewer the Critics deals 3 damage to any target.

Priest of Forgotten Gods

{T}, Sacrifice two other creatures: Any number of target players each lose 2 life and sacrifice a creature. You add {B}{B} and draw a card.

Reassembling Skeleton

{1}{B}: Return Reassembling Skeleton from your graveyard to the battlefield tapped.

Dragonskull Summit

Dragonskull Summit enters the battlefield tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

Go for the Throat

Lava Coil

Lava Coil deals 4 damage to target creature. If that creature would die this turn, exile it instead.