Autonomous Assembler

Prototype exists to resolve a specific tension: a card that wants to be a body early and a payoff late, without splitting into two prints. This is the mechanic used exactly as intended. Cast for its printed , it lands as a 4/5 with vigilance and an activated ability that grows any Assembly-Worker you control, including itself; cast for the prototype cost, it arrives as a 2/2 that keeps every one of those abilities and its Assembly-Worker type. The same card fills a cheap slot on the early turns and the top-end slot later, and the counter engine works from either entry point because prototype preserves the text box regardless of which cost paid for it. Vigilance is what makes the growth ability worth having on an attacker: because the creature does not tap to attack, it can swing and still spend its , in the same turn, so the counter you buy does not cost you a combat step. The ability can target itself or any other Assembly-Worker, so an early prototype body can feed counters into a later hardcast one, or a board of them can pump each other in sequence, which is where running multiples starts to compound. Neither mode is a strong rate taken alone, and that is the wager prototype asks you to make: you are not buying a good two-drop or a good five-drop, you are buying the option to be whichever the game needs, with a payload that rewards stacking the same creature type.