Thought-Knot Seer

({C} represents colorless mana.)
When this creature enters, target opponent reveals their hand. You choose a nonland card from it and exile that card.
When this creature leaves the battlefield, target opponent draws a card.

Warping Wail

({C} represents colorless mana.)
Choose one —
• Exile target creature with power or toughness 1 or less.
• Counter target sorcery spell.
• Create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this token: Add {C}."

Karn's Sylex

Karn's Sylex enters tapped.
Players can't pay life to cast spells or to activate abilities that aren't mana abilities.
{X}, {T}, Exile Karn's Sylex: Destroy each nonland permanent with mana value X or less. Activate only as a sorcery.

Soul-Guide Lantern

When this artifact enters, exile target card from a graveyard.
{T}, Sacrifice this artifact: Exile each opponent's graveyard.
{1}, {T}, Sacrifice this artifact: Draw a card.

Spatial Contortion

({C} represents colorless mana.)
Target creature gets +3/-3 until end of turn.

Matter Reshaper

({C} represents colorless mana.)
When this creature dies, reveal the top card of your library. You may put that card onto the battlefield if it's a permanent card with mana value 3 or less. Otherwise, put that card into your hand.

Zhalfirin Void

When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {C}.

Endbringer

Untap this creature during each other player's untap step.
{T}: This creature deals 1 damage to any target.
{C}, {T}: Target creature can't attack or block this turn.
{C}{C}, {T}: Draw a card.

Forsaken Monument

Colorless creatures you control get +2/+2.
Whenever you tap a permanent for {C}, add an additional {C}.
Whenever you cast a colorless spell, you gain 2 life.

Stonecoil Serpent

Reach, trample, protection from multicolored
This creature enters with X +1/+1 counters on it.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Scavenger Grounds

{T}: Add {C}.
{2}, {T}, Sacrifice a Desert: Exile all graveyards.

Field of Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Destroy target nonbasic land an opponent controls. Each player searches their library for a basic land card, puts it onto the battlefield, then shuffles.

Bonders' Enclave

{T}: Add {C}.
{3}, {T}: Draw a card. Activate only if you control a creature with power 4 or greater.

Reality Smasher

({C} represents colorless mana.)
Trample, haste
Whenever this creature becomes the target of a spell an opponent controls, counter that spell unless its controller discards a card.

Eldrazi Mimic

Whenever another colorless creature you control enters, you may change this creature's base power and toughness to that creature's power and toughness until end of turn.

Ugin, the Spirit Dragon

+2: Ugin deals 3 damage to any target.
−X: Exile each permanent with mana value X or less that's one or more colors.
−10: You gain 7 life, draw seven cards, then put up to seven permanent cards from your hand onto the battlefield.

Ruins of Oran-Rief

This land enters tapped.
{T}: Add {C}. ({C} represents colorless mana.)
{T}: Put a +1/+1 counter on target colorless creature that entered this turn.

Liberator, Urza's Battlethopter

Flash
Flying
You may cast colorless spells and artifact spells as though they had flash.
Whenever you cast a spell, if the amount of mana spent to cast that spell is greater than Liberator's power, put a +1/+1 counter on Liberator.

Ugin, the Ineffable

Colorless spells you cast cost {2} less to cast.
+1: Exile the top card of your library face down and look at it. Create a 2/2 colorless Spirit creature token. When that token leaves the battlefield, put the exiled card into your hand.
−3: Destroy target permanent that's one or more colors.

Blast Zone

This land enters with a charge counter on it.
{T}: Add {C}.
{X}{X}, {T}: Put X charge counters on this land.
{3}, {T}, Sacrifice this land: Destroy each nonland permanent with mana value equal to the number of charge counters on this land.

Pithing Needle

As this artifact enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.

Ghostfire Blade

Equipped creature gets +2/+2.
Equip {3}
This Equipment's equip ability costs {2} less to activate if it targets a colorless creature.

Wastes

Mutavault

{T}: Add {C}.
{1}: This land becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Damping Sphere

If a land is tapped for two or more mana, it produces {C} instead of any other type and amount.
Each spell a player casts costs {1} more to cast for each other spell that player has cast this turn.