Quillmane Baku is a common Creature — Spirit card from Betrayers of Kamigawa (BOK), collector number 48. Current market price: $0.22 (foil $0.20), TCGplayer market prices via Scryfall.
Whenever you cast a Spirit or Arcane spell, you may put a ki counter on this creature. {1}, {T}, Remove X ki counters from this creature: Return target creature with mana value X or less to its owner's hand.