Chartooth Cougar is a common Creature — Cat Beast card from Masters 25 (A25), collector number 125. Current market price: $0.05 (foil $0.31), TCGplayer market prices via Scryfall.
{R}: This creature gets +1/+0 until end of turn. Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)