Case of the Pilfered Proof

Whenever a Detective enters the battlefield under your control and whenever a Detective you control is turned face up, put a +1/+1 counter on it.

To solve — You control three or more Detectives. (If unsolved, solve at the beginning of your end step.)

Solved — If one or more tokens would be created under your control, those tokens plus a Clue token are created instead. (It's an artifact with ", Sacrifice this artifact: Draw a card.")