Gideon's Battle Cry is a rare Sorcery card from War of the Spark (WAR), collector number 267. Current market price: $0.10, TCGplayer market prices via Scryfall.
Put a +1/+1 counter on each creature you control. You may search your library and/or graveyard for a card named Gideon, the Oathsworn, reveal it, and put it into your hand. If you search your library this way, shuffle.