ProwessProwess is a triggered ability. “Prowess” means “Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.”
If a creature has multiple instances of prowess, each triggers separately. (CR 702.108) (Whenever you
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) a noncreature spell, this creature gets +1/+1 until end of turn.)
Creatures with power less than this creature's power can't block it. // Distribute X +1/+1
countersTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) among any number of target creatures you control. (Then
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) this card. You may
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) the creature later from
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13).)