Imperial Dragoon, Aidos

Ward—Discard 2 cards
Instants you cast on your opponents' turns gain Cascade. (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Each time you cast a card from Exile you can draw 1 card, then discard 1 card and take 1 damage.