Catacomb Sifter

Devoid (This card has no color.)
When this creature enters, create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this token: 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.)

Pioneer Masters

Battle for Zendikar

Devoid (This card has no color.)
When Catacomb Sifter enters the battlefield, put a 1/1 colorless Eldrazi Scion creature token onto the battlefield. It has "Sacrifice this creature: Add {1} to your mana pool."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.)

Devoid works in all zones, not just on the battlefield.

Eldrazi Scions are similar to Eldrazi Spawn, seen in the Zendikar block. Note that Eldrazi Scions are 1/1, not 0/1.

A card with devoid is just colorless. It's not colorless and the colors of mana in its mana cost.

Cards with devoid use frames that are variations of the transparent frame traditionally used for Eldrazi. The top part of the card features some color over a background based on the texture of the hedrons that once imprisoned the Eldrazi. This coloration is intended to aid deckbuilding and game play.

Eldrazi and Scion are each separate creature types. Anything that affects Eldrazi will affect these tokens, for example.

If a card loses devoid, it will still be colorless. This is because effects that change an object's color (like the one created by devoid) are considered before the object loses devoid.

Other cards and abilities can give a card with devoid color. If that happens, it's just the new color, not that color and colorless.

Sacrificing an Eldrazi Scion creature token to add {C} is a mana ability. It doesn't use the stack and can't be responded to.

Some instants and sorceries that create Eldrazi Scions require targets. If all targets for such a spell have become illegal by the time that spell tries to resolve, the spell won't resolve and none of its effects will happen. You won't get any Eldrazi Scions.