Len Vuren, Master Investigator

Len Vuren enters the battlefield with X +1/+1 counters on him, where X is the number of clues you control.
Remove a +1/+1 counter from Len Vuren: Investigate (Put a colorless Clue artifact token onto the battlefield with "{2}, sacrifice this artifact: Draw a card."
Whenever you sacrifice a clue, creatures you control get +1/+1 until end of turn.