Prototype

MTG Mechanic

The Brothers' War features prototype cards, which have a mechanic that represents an artificer's work in different stages of development. Each prototype card is an artifact creature which has a secondary set of mana cost, power, and toughness characteristics that are inset in the top of its text box. It can be cast using either its normal characteristics or it can be cast as a smaller "prototyped" version of itself that uses the secondary characteristics instead.