Ageless Sentinels is a rare Creature — Wall card from Scourge (SCG), collector number 1. Current market price: $0.28 (foil $1.31), TCGplayer market prices via Scryfall.
Defender (This creature can't attack.) Flying When this creature blocks, it becomes a Bird Giant, and it loses defender. (It's no longer a Wall. This effect lasts indefinitely.)