Ultron Drone

One card, two robots, both the same tribe: that is the payoff this design is built to deliver. The 2/3 body is deliberately unremarkable so the mechanic can do the talking. Six mana buys two counters and a 2/2 Robot Villain token, which reads as expensive until the parenthetical does its work: deploy the drone and activate on the same turn, and the three already sunk into casting it comes off the bill, so the body and the upgrade both land inside a single tempo curve instead of forcing you to hold mana across two turns. The once-per-ability clause is the governor here. Each drone earns exactly one upgrade into a 4/5 plus a token, then it is spent no matter how much mana sits open, which is precisely what keeps a level-up mechanic from curving into a repeatable pump that snowballs past answering. What you get out of it is a mana sink stapled to a real creature that also leaves a spare body behind, unusually dense value for a colorless three-drop that costs no color to slot anywhere. The token sharing the Robot Villain type is not incidental; anything that rewards the tribe counts both halves, and the design is clearly engineered around producing two members of it from a single card.