Magmablood Archaic (SOS-123) [Secrets of Strixhaven]

Trample, reach

Converge — This creature enters with a +1/+1 counter on it for each color of mana spent to cast it.

Whenever you cast an instant or sorcery spell, creatures you control get +1/+0 until end of turn for each color of mana spent to cast that spell.