Chaos Space Marines may dedicate themselves to one of the Chaos powers by bearing their Mark. The effect of each Mark of Chaos is described below. In addition, bearing the Mark of a Chaos power allows the model to take certain items of Wargear and can affect what units count as troops in the main army list.

Mark of Khorne: Models bearing this Mark add +1 to their Strength.

Mark of Nurgle: Models bearing this Mark add +1 to their Toughness.

Mark of Slaanesh: Models bearing this Mark add +1 to their Attacks.

Mark of Tzeentch: Models bearing this Mark don't need to pass a Psychic test to use a psychic power. They may use it automatically.

Mark of Chaos Undivided: Models bearing this Mark may re-roll failed Morale checks.