Wild-Magic Sorcerer

The first spell you cast from exile each turn will have cascade, even if it's not the first spell you've cast that turn.

If the card has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

If, while resolving the cascade ability from the first spell you cast from exile in a turn, you cascade into a second Wild-Magic Sorcerer, the spell will not cascade again.

If a spell with cascade is countered, the cascade ability will still resolve normally.

You exile the cards face up. All players will be able to see them.

A spell's mana value is determined only by its mana cost. Ignore any alternative costs, additional costs, cost increases, or cost reductions. For example, Wild-Magic Sorcerer's mana value is always 4.

Due to a recent rules change to cascade, not only do you stop exiling cards if you exile a nonland card with lesser mana value than the spell with cascade, but the resulting spell you cast must also have lesser mana value. Previously, in cases where a card's mana value differed from the resulting spell, such as with some modal double-faced cards or cards with an Adventure, you could cast a spell with a higher mana value than the exiled card.

If you control more than one Wild-Magic Sorcerer, the first spell you cast from exile will have that many instances of cascade, each of which will trigger separately.

When the cascade ability resolves, you must exile cards. The only optional part of the ability is whether or not you cast the last card exiled.