Sludge Crawler — ruling 1

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.

Sludge Crawler — ruling 2

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

Sludge Crawler — ruling 3

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.

Sludge Crawler — ruling 4

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

Sludge Crawler — ruling 5

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.

Sludge Crawler — ruling 6

The card exiled by the ingest ability is exiled face up.

Sludge Crawler — ruling 7

If the player has no cards in their library when the ingest ability resolves, nothing happens. That player won't lose the game (until they have to draw a card from an empty library).

Sludge Crawler : règles, fonctionnement et interactions (MTG)

Sludge Crawler is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

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.) : This creature gets +1/+1 until end of turn.

How it works : Sludge Crawler

Original English text — Wizards of the Coast / Scryfall

#1August 25, 2015· Wizards of the Coast
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.
No other card is named in this ruling.
#2August 25, 2015· Wizards of the Coast
A card with devoid is just colorless. It's not colorless and the colors of mana in its mana cost.
No other card is named in this ruling.
#3August 25, 2015· Wizards of the Coast
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.
No other card is named in this ruling.
#4August 25, 2015· Wizards of the Coast
Devoid works in all zones, not just on the battlefield.
No other card is named in this ruling.
#5August 25, 2015· Wizards of the Coast
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.
No other card is named in this ruling.
#6August 25, 2015· Wizards of the Coast
The card exiled by the ingest ability is exiled face up.
No other card is named in this ruling.
#7August 25, 2015· Wizards of the Coast
If the player has no cards in their library when the ingest ability resolves, nothing happens. That player won't lose the game (until they have to draw a card from an empty library).
No other card is named in this ruling.