Herald of Kozilek

Devoid (This card has no color.)
Colorless spells you cast cost {1} less to cast.

Void Grafter

Devoid (This card has no color.)
Flash (You may cast this spell any time you could cast an instant.)
When Void Grafter enters the battlefield, another target creature you control gains hexproof until end of turn.

Essence Depleter

Devoid (This card has no color.)
{1}{C}: Target opponent loses 1 life and you gain 1 life. ({C} represents colorless mana.)

Brood Monitor

Devoid (This card has no color.)
When Brood Monitor enters the battlefield, create three 1/1 colorless Eldrazi Scion creature tokens. They have "Sacrifice this creature: Add {C}."

Eldrazi Displacer

Devoid (This card has no color.)
{2}{C}: Exile another target creature, then return it to the battlefield tapped under its owner's control. ({C} represents colorless mana.)

Cultivator Drone

Devoid (This card has no color.)
{T}: Add {C}. Spend this mana only to cast a colorless spell, activate an ability of a colorless permanent, or pay a cost that contains {C}. ({C} represents colorless mana.)

Fathom Feeder

Devoid (This card has no color.)
Deathtouch
Ingest (Whenever this creature deals combat damage to a player, that player exiles the top card of their library.)
{3}{U}{B}: Draw a card. Each opponent exiles the top card of their library.

Growth Spasm

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Create a 0/1 colorless Eldrazi Spawn creature token. It has "Sacrifice this creature: Add {C}."

Azlask, the Swelling Scourge

Whenever Azlask, the Swelling Scourge or another colorless creature you control dies, you get an experience counter.
{W}{U}{B}{R}{G}: Creatures you control get +X/+X until end of turn, where X is the number of experience counters you have. Scions and Spawns you control gain indestructible and annihilator 1 until end of turn.

Immobilizer Eldrazi

Devoid (This card has no color.)
{2}{C}: Each creature with toughness greater than its power can't block this turn. ({C} represents colorless mana.)

Molten Nursery

Devoid (This card has no color.)
Whenever you cast a colorless spell, Molten Nursery deals 1 damage to any target.

Nettle Drone

Devoid (This card has no color.)
{T}: Nettle Drone deals 1 damage to each opponent.
Whenever you cast a colorless spell, untap Nettle Drone.

Ruination Guide

Devoid (This card has no color.)
Ingest (Whenever this creature deals combat damage to a player, that player exiles the top card of their library.)
Other colorless creatures you control get +1/+0.

Catacomb Sifter

Devoid (This card has no color.)
When Catacomb Sifter enters the battlefield, create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this creature: Add {C}."
Whenever another creature you control dies, scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Flayer Drone

Devoid (This card has no color.)
First strike
Whenever another colorless creature enters the battlefield under your control, target opponent loses 1 life.