Monastery Mentor

The token engine is the whole evolution. Prowess had already shown up as a way to reward spell-heavy decks with a temporary buff, but pairing a single creature's prowess with a second trigger that mints a fresh prowess body on every noncreature spell turns one cantrip into a battlefield problem that compounds. Cast a spell and the 2/2 swings as a 3/3 while a 1/1 Monk arrives; the Monk also has prowess, so the next spell pumps everything the engine has produced at once. That exponential curve is the reason a single turn with two or three cheap spells can convert an empty board into lethal, and the threat does not sit on the stack where a counterspell can answer it (the tokens land before combat, already resolved). The cost of all that is the body itself, a 2/2 that dies to nearly any removal, and the tokens follow only as long as it lives to see your spells cast. Kill it in response to nothing and the engine stops before it starts. That fragility is the only governor on a card that otherwise asks for one perfect turn. The lineage points forward more than back: it proved you could build an aggressive deck out of cheap interaction and a payoff that rewards casting those answers, the spell-velocity threat that later cards keep circling.