Curious Homunculus

: Add. Spend this mana only to cast an instant or sorcery spell.At the beginning of your upkeep, if there are three or more instant and/or sorcery cards in your graveyard, transform Curious Homunculus.

Prowess(Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)Instant and sorcery spells you cast costless to cast.