Amunet, One with Nix

Flying, ward - Put a card from your hand on top
of your library.
When you cast an enchantment spell for the first
time each turn, exile cards from the top of your library until you exile an instant or sorcery with
lesser mana value. You may cast it without
paying its mana cost for as long as it remains
exiled. Put the rest on the bottom of your library
in a random order.