Ruins of Oran-Rief

Ruins of Oran-Rief enters tapped.
{T}: Add {C}. ({C} represents colorless mana.)
{T}: Put a +1/+1 counter on target colorless creature that entered this turn.

Relic Golem

Relic Golem can't attack or block unless an opponent has eight or more cards in their graveyard.
{2}, {T}: Target player mills two cards. (They put the top two cards of their library into their graveyard.)

Thought-Knot Seer

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

Barrage Tyrant

Devoid (This card has no color.)
{2}{R}, Sacrifice another colorless creature: Barrage Tyrant deals damage equal to the sacrificed creature's power to any target.

Eldrazi Obligator

Devoid (This card has no color.)
When you cast this spell, you may pay {1}{C}. If you do, gain control of target creature until end of turn, untap that creature, and it gains haste until end of turn. ({C} represents colorless mana.)
Haste

Bonders' Enclave

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

Dread Defiler

Devoid (This card has no color.)
{3}{C}, Exile a creature card from your graveyard: Target opponent loses life equal to the exiled card's power. ({C} represents colorless mana.)

Dust Stalker

Devoid (This card has no color.)
Haste
At the beginning of each end step, if you control no other colorless creatures, return Dust Stalker to its owner's hand.

Hewed Stone Retainers

Cast this spell only if you've cast another spell this turn.

Ghostfire Blade

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

Ramunap Ruins

{T}: Add {C}.
{T}, Pay 1 life: Add {R}.
{2}{R}{R}, {T}, Sacrifice a Desert: Ramunap Ruins deals 2 damage to each opponent.

Spatial Contortion

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

Eldrazi Mimic

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

Unnatural Endurance

Devoid (This card has no color.)
Target creature gets +2/+0 until end of turn. Regenerate it.

Reality Smasher

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