Periwinkle’s Frozen Lightning

Delve (This card costs {x} less to cast where {x} is
the total number of instant or sorceries in your
graveyard)

Target opponent mills nine cards, then you may cast
an instant or sorcery from that players graveyard
without paying its mana cost. If that card would
would then be put in a graveyard, exile it instead.

What can I say? They made me frosty.