Tester of the Tangential (SOS-069) [Secrets of Strixhaven]

Increment (Whenever you cast a spell, if the amount of mana you spent is greater than this creature's power or toughness, put a +1/+1 counter on this creature.)

At the beginning of combat on your turn, you may pay X. When you do, move X +1/+1 counters from this creature onto another target creature.