Dark Depths

Dark Depths enters with ten ice counters on it.
{3}: Remove an ice counter from Dark Depths.
When Dark Depths has no ice counters on it, sacrifice it. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

Thespian's Stage

{T}: Add {C}.
{2}, {T}: Thespian's Stage becomes a copy of target land, except it has this ability.

Elvish Spirit Guide

Exile Elvish Spirit Guide from your hand: Add {G}.

Dark Ritual

Expedition Map

{2}, {T}, Sacrifice this artifact: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Swamp

Vampire Hexmage

First strike
Sacrifice Vampire Hexmage: Remove all counters from target permanent.

Simian Spirit Guide

Exile Simian Spirit Guide from your hand: Add {R}.

Thoughtseize

Target player reveals their hand. You choose a nonland card from it. That player discards that card. You lose 2 life.

Cabal Ritual

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

Not of This World

Counter target spell or ability that targets a permanent you control.
This spell costs {7} less to cast if it targets a spell or ability that targets a creature you control with power 7 or greater.

Inquisition of Kozilek

Target player reveals their hand. You choose a nonland card from it with mana value 3 or less. That player discards that card.

Chromatic Sphere

{1}, {T}, Sacrifice Chromatic Sphere: Add one mana of any color. Draw a card.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Aether Snap

Remove all counters from all permanents and exile all tokens.

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.