Augment Monsters are one of the required parts when performing a Cross Summon for a Cross Monster. Augment Monsters are used from the hand with monsters on the field.
When you perform a Cross Summon, you multiply the Level of the Augment Monster in your hand with the total Levels of the monsters on your field and they must equal the Cross Product of the monster your are attempting to summon. All monsters used in the summon are placed in one of the 5 Cross Zones behind the Spell & Trap Card Zone and they become the Cross Materials for the summoned monster.
Most Augment Monsters posses a Cross Zone Effect, which is an effect that is continuous while they are in your Cross Zone.
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