Obscura Ascendancy - Streets of New Capenna

Whenever you cast a spell, if its mana value is equal to the number of soul counters on Obscura Ascendancy plus one, put a soul counter on Obscura Ascendancy, then create a 2/2 white Spirit creature token with flying.
As long as Obscura Ascendancy has five or more soul counters on it, Spirits you control get +3/+3.