This spell costsless to cast for each card you've cycled or discarded this turn.
Cycling( , Discard this card: Draw a card.)
7/14/2017 Hollow One’s cost is reduced even if the cards you’ve cycled or discarded aren’t in your graveyard.
7/14/2017 Once you’ve discarded three cards, Hollow One costs to cast. It won’t stop at or cost negative amounts of mana.
7/14/2017 Hollow One’s first ability doesn’t give you permission to discard cards. You’ll need another effect that instructs or allows you to discard them.