Eidolon of Rippling Waters

Islandwalk, Forestwalk
Whenever Eidolon of Rippling Waters 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 exiled cards on the bottom of your library in a random order.)