Prowess

Prowess is a triggered ability that gives the creature +1/+1 until end of turn, when you cast a non-creature spell.

Comprehensive Rules
702.107. Prowess

702.107a Prowess is a triggered ability. “Prowess” means “Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.”

702.107b If a creature has multiple instances of prowess, each triggers separately.