Comprehensive Rules
702.85a
Cascade is a triggered ability that functions only while the spell with cascade is on the stack. âCascadeâ means âWhen you cast this spell, exile cards from the top of your library until you exile a nonland card whose mana value is less than this spellâs mana value. You may cast that card without paying its mana cost if the resulting spellâs mana value is less than this spellâs mana value. Then put all cards exiled this way that werenât cast on the bottom of your library in a random order.â