Finest Hour is a rare Enchantment card from Alara Reborn (ARB), collector number 126. Current market price: $0.78 (foil $9.10), TCGplayer market prices via Scryfall.
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.) Whenever a creature you control attacks alone, if it's the first combat phase of the turn, untap that creature. After this phase, there is an additional combat phase.