Cabal Ritual

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

Shred Memory

Exile up to four target cards from a single graveyard.
Transmute {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Manamorphose

Add two mana in any combination of colors.
Draw a card.

Rite of Flame

Add {R}{R}, then add {R} for each card named Rite of Flame in each graveyard.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Deep Analysis

Target player draws two cards.
Flashback—{1}{U}, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Sulfur Vent

Sulfur Vent enters the battlefield tapped.
{T}: Add {B}.
{T}, Sacrifice Sulfur Vent: Add {U}{R}.

Clear the Mind

Target player shuffles their graveyard into their library.
Draw a card.

Khalni Garden

Khalni Garden enters the battlefield tapped.
When Khalni Garden enters the battlefield, create a 0/1 green Plant creature token.
{T}: Add {G}.

Chromatic Star

{1}, {T}, Sacrifice Chromatic Star: Add one mana of any color.
When Chromatic Star is put into a graveyard from the battlefield, draw a card.

Night's Whisper

Dark Ritual

Ideas Unbound

Draw three cards. Discard three cards at the beginning of the next end step.

Perilous Research

Draw two cards, then sacrifice a permanent.

Exhume

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

Duress

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

Street Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Cycling—Pay 2 life. (Pay 2 life, Discard this card: Draw a card.)

Weather the Storm

You gain 3 life.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Irrigation Ditch

Irrigation Ditch enters the battlefield tapped.
{T}: Add {W}.
{T}, Sacrifice Irrigation Ditch: Add {G}{U}.

Seething Song

Compulsive Research

Target player draws three cards. Then that player discards two cards unless they discard a land card.

Geothermal Crevice

Geothermal Crevice enters the battlefield tapped.
{T}: Add {R}.
{T}, Sacrifice Geothermal Crevice: Add {B}{G}.

Peat Bog

Peat Bog enters the battlefield 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.