Geothermal Crevice

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

Saprazzan Skerry

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

Manamorphose

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

Island

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.

Pentad Prism

Sunburst (This enters with a charge counter on it for each color of mana spent to cast it.)
Remove a charge counter from Pentad Prism: Add one mana of any color.

Contentious Plan

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Draw a card.

Infectious Inquiry

You draw two cards and you lose 2 life. Each opponent gets a poison counter.

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Cabal Ritual

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

Vraska's Fall

Each opponent sacrifices a creature or planeswalker of their choice and gets a poison counter.

Experimental Synthesizer

When Experimental Synthesizer enters or leaves the battlefield, exile the top card of your library. Until end of turn, you may play that card.
{2}{R}, Sacrifice Experimental Synthesizer: Create a 2/2 white Samurai creature token with vigilance. Activate only as a sorcery.

Prologue to Phyresis

Each opponent gets a poison counter.
Draw a card.

Seat of the Synod

Weather the Storm

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

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.

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Sandstone Needle

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

Duress

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

Dark Ritual

Virulent Wound

Put a -1/-1 counter on target creature. When that creature dies this turn, its controller gets a poison counter.

Pyroblast

Choose one —
• Counter target spell if it's blue.
• Destroy target permanent if it's blue.

Experimental Augury

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)