Selyla, Echoed Power

Whenever you put an instant or sorcery into your
hand or cast one from your graveyard, put a
+1/+1 counter on Selyla, Echoed Power.
{2}, {t}: Empower X, where X is the number of
+1/+1 counters on Selyla (Any number of
instants or sorceries in your graveyard with a
combined converted mana cost of X can be cast
this turn and when they would enter the
graveyard, exile them instead. They cost {1} less.)