Solidarity of Heroes 
Instant
Strive — This spell costs 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.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL