Sifter of Skulls 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.) Whenever another nontoken creature you control dies, create a 1/1 colorless Eldrazi Scion creature token. It has "Sacrifice this token: Add ." ( represents colorless mana.)

Complete guide

Sifter of Skulls is a versatile Eldrazi creature that ensures your fallen soldiers leave behind a valuable legacy. By turning death into resources, it provides both a board presence and a mana advantage in any colorless or black-focused deck.

Harnessing the Devoid Mechanic

Despite costing black mana to cast, Sifter of Skulls possesses the Devoid keyword, meaning it is entirely colorless in all zones. This is important for interactions that care about colorless permanents. Its main ability triggers whenever 'another nontoken creature' you control dies, rewarding you for the natural cycle of combat or your own sacrifice outlets.

Generating Eldrazi Scions

When the conditions are met, you create a 1/1 Eldrazi Scion token. These tokens are unique because they can be sacrificed at any time you could activate a mana ability to add one colorless mana ({C}) to your mana pool. This allows Sifter of Skulls to effectively 'refund' mana or jumpstart higher-cost spells whenever your other creatures perish.

Key Timing and Restrictions

It is crucial to remember that Sifter of Skulls only triggers for nontoken creatures. If an Eldrazi Scion token is destroyed or sacrificed, it will not trigger the ability to create a new one. Additionally, the creature must actually reach the graveyard from the battlefield for the 'dies' trigger to occur; if the creature is exiled instead, no token is created.

Strategic Implementation

This card shines in decks that utilize 'aristocrat' strategies, where you frequently sacrifice your own creatures for value. By replacing those creatures with Scions, you maintain a board state that can either pressure the opponent with 1/1 attackers or accelerate into massive late-game threats.

Interaction examples

The Value Engine

Solemn Simulacrum

If you control both creatures and Solemn Simulacrum dies, two triggers are put onto the stack: the Simulacrum's draw ability and the Sifter's token generation. You will draw a card and create a 1/1 Eldrazi Scion, effectively replacing your fallen creature with both card advantage and mana ramp.

Double the Harvest

Roaming Throne

If you name 'Eldrazi' as Roaming Throne enters, its replacement effect will apply to Sifter of Skulls. When another nontoken creature you control dies, Sifter of Skulls' ability triggers twice. You will create two Eldrazi Scion tokens instead of one, doubling your mana potential and board presence.

Token Chain Limits

Eldrazi Scion

If you sacrifice an Eldrazi Scion to add {C} to your mana pool while Sifter of Skulls is on the battlefield, the Sifter will not trigger. This is because the Sifter specifically looks for 'nontoken' creatures. This prevents an infinite loop of mana generation from a single token.

Guide written with AI from the official text and rulings. Official English text prevails.