Processor Assault — ruling 1

You must put exactly one card an opponent owns from exile into that player’s graveyard to cast Processor Assault. You can’t cast it without doing so, and you can’t put multiple exiled cards into their owners’ graveyards this way.

Processor Assault — ruling 2

Players can respond to Processor Assault only after it’s been cast and all of its costs have been paid. No one can try to remove the card from exile to stop you from casting the spell.

Processor Assault — ruling 3

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.

Processor Assault — ruling 4

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

Processor Assault — ruling 5

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.

Processor Assault — ruling 6

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

Processor Assault — ruling 7

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.

Processor Assault — ruling 8

If a spell or ability requires that you put more than one exiled card into the graveyard, you may choose cards owned by different opponents. Each card chosen will be put into its owner’s graveyard.

Processor Assault : règles, fonctionnement et interactions (MTG)

Processor Assault 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.) As an additional cost to cast this spell, put a card an opponent owns from exile into that player's graveyard. Processor Assault deals 5 damage to target creature.

How it works : Processor Assault

Original English text — Wizards of the Coast / Scryfall

#1August 25, 2015· Wizards of the Coast
You must put exactly one card an opponent owns from exile into that player’s graveyard to cast Processor Assault. You can’t cast it without doing so, and you can’t put multiple exiled cards into their owners’ graveyards this way.
No other card is named in this ruling.
#2August 25, 2015· Wizards of the Coast
Players can respond to Processor Assault only after it’s been cast and all of its costs have been paid. No one can try to remove the card from exile to stop you from casting the spell.
No other card is named in this ruling.
#3August 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.
#4August 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.
#5August 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.
#6August 25, 2015· Wizards of the Coast
Devoid works in all zones, not just on the battlefield.
No other card is named in this ruling.
#7August 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.
#8August 25, 2015· Wizards of the Coast
If a spell or ability requires that you put more than one exiled card into the graveyard, you may choose cards owned by different opponents. Each card chosen will be put into its owner’s graveyard.
No other card is named in this ruling.
#9August 25, 2015· Wizards of the Coast
If a replacement effect will cause cards that would be put into a graveyard from anywhere to be exiled instead (such as the one created by Anafenza, the Foremost), you can still put an exiled card into its opponent’s graveyard. The card becomes a new object and remains in exile. In this situation, you can’t use a single exiled card if required to put more than one exiled card into the graveyard. Conversely, you could use the same card in this situation if two separate spells or abilities each required you to put a single exiled card into its owner’s graveyard.
No other card is named in this ruling.
#10August 25, 2015· Wizards of the Coast
You can’t look at face-down cards in exile unless an effect allows you to.
No other card is named in this ruling.
#11August 25, 2015· Wizards of the Coast
Face-down cards in exile are grouped using two criteria: what caused them to be exiled face down and when they were exiled face down. If you want to put a face-down card in exile into its owner’s graveyard, you must first choose one of these groups and then choose a card from within that group at random. For example, say an artifact causes your opponent to exile their hand of three cards face down. Then on a later turn, that artifact causes your opponent to exile another two cards face down. If you use Wasteland Strangler to put one of those cards into their graveyard, you would pick the first or second pile and put a card chosen at random from that pile into the graveyard.
No other card is named in this ruling.