Instant and sorcery spells you cast cost less to cast.

Whenever you cast an instant or sorcery spell, put a charge counter on Primal Amulet. Then if there are four or more charge counters on it, you may remove those counters and transform it.
//
(Transforms from Primal Amulet.)
: Add one mana of any color to your mana pool. When that mana is spent to cast an instant or sorcery spell, copy that spell and you may choose new targets for the copy.