Frisk Dreemurr, Magic Student

Whenever you cast a red spell, put a +1/+1
counter on Frisk Dreemurr, Magic Student.
At end of combat, if Frisk Dreemurr blocked
this turn, remove all +1/+1 counters from them
and deal damage to the number of counters
removed in this way to any target. Then, if you
removed three or more counters in this way, exile
Frisk, then return them to the battlefield
transformed under their owner's control.