Brightfield Glider is a common Creature — Possum Mount card from Aetherdrift (DFT), collector number 4. Current market price: $0.11 (foil $0.19), TCGplayer market prices via Scryfall.
Vigilance Whenever this creature attacks while saddled, it gets +1/+2 and gains flying until end of turn. Saddle 3 (Tap any number of other creatures you control with total power 3 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)