Yidris, Maelstrom Wielder

Trample
Whenever Yidris, Maelstrom Wielder deals
combat damage to a player, as you cast spells
from your hand this turn, they gain cascade.
(When you cast the 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 exile cards on the
bottom of your library in a random order.)