Solidarity of Heroes is a uncommon Instant card from Journey into Nyx (JOU), collector number 141. Current market price: $0.39 (foil $6.54), TCGplayer market prices via Scryfall.
Strive — This spell costs {1}{G} more to cast for each target beyond the first. Choose any number of target creatures. Double the number of +1/+1 counters on each of them.