Cascade is a ability on some Alara Reborn non-permanent spells that triggers when the spell is played. This cascade triggered ability will go on the stack on top of the spell with the ability, and because of this the trigger will resolve first. When the triggered ability resolves the controller of the ability will exile cards on top of his or her library until a card is exiled that has a converted mana cost that is lower than the spell with the cascade ability. This player can then play this last card without paying its mana cost. Then all of the cards that have been exiled by this ability are put on the bottom of the library they came from in a random order.

Playing the last card to be revealed by the cascade ability is not mandatory, the controller of the ability can choose to not play it. If they do, then this card is put on the bottom of its owners library with the other cards that were exiled by this ability.

Because the cascade trigger resolves before the spell that it came from, the card that is revealed and played when this trigger resolves will also resolve before this original spell. This is important as some choices may be different because of this order. For example, if a player were to play a Bloodbraid Elf and spell that could target a creature is revealed, the Bloodbraid Elf itself could not be targeted as it is not in play yet.

Alternate costs and additional costs of the revealed spell are not paid by the Cascade ability. Additionally, mana costs with a variable in them, like X, will have the value of X be zero.

Playing the last revealed card does count as playing a spell, so abilities that trigger when a spell is played will trigger. However, copies of spells that are put on the stack will not trigger cascade abilities. This is because the cascade ability only triggers when the spell with cascade is played.