Unbreakable Formation is a rare Instant card from The Brothers' War Commander (BRC), collector number 78. Current market price: $0.99, TCGplayer market prices via Scryfall.
Creatures you control gain indestructible until end of turn. Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.