Gideon, Champion of Justice is a mythic Legendary Planeswalker — Gideon card from Gatecrash (GTC), collector number 13. Current market price: $0.41 (foil $3.37), TCGplayer market prices via Scryfall.
+1: Put a loyalty counter on Gideon for each creature target opponent controls. 0: Until end of turn, Gideon becomes a Human Soldier creature with power and toughness each equal to the number of loyalty counters on him and gains indestructible. He's still a planeswalker. Prevent all damage that would be dealt to him this turn. −15: Exile all other permanents.