Gideon, the Oathsworn is a mythic Legendary Planeswalker — Gideon card from War of the Spark (WAR), collector number 265. Current market price: — (foil $0.84), TCGplayer market prices via Scryfall.
Whenever you attack with two or more non-Gideon creatures, put a +1/+1 counter on each of those creatures. +2: Until end of turn, Gideon becomes a 5/5 white Soldier creature that's still a planeswalker. Prevent all damage that would be dealt to him this turn. (He can't attack if he was cast this turn.) −9: Exile Gideon and each creature your opponents control.