Strength of the Tajuru is a rare Instant card from Worldwake (WWK), collector number 113. Current market price: $0.42 (foil $1.56), TCGplayer market prices via Scryfall.
Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.) Choose target creature, then choose another target creature for each time this spell was kicked. Put X +1/+1 counters on each of them.