Discover

Discover
Keyword Action
Introduced	The Lost Caverns of Ixalan
Last used	Marvel Super Heroes Commander
Reminder Text	Discover N (Exile cards from the top of your library until you exile a nonland card with mana value N or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)
Scryfall statistics
32 cards 12.5% 3.1% 9.4% 6.3% 34.4% 15.6% 18.8%
2 discover synergy cards 50% 50%

Discover is a keyword action introduced in The Lost Caverns of Ixalan.

Description

Like cascade, discover exiled cards through the top of the controller's library for a valid nonland card and allows them to cast it for free, returning other cards exiled this way to the bottom of the library in a random order.

Discover is a revamped successor of Cascade with more design space. Compared to cascade, discover:

1. Is a keyword action that can be put on various triggers rather than being restricted to cast triggers.
2. Specifies a mana value independently instead of being tied to the cascading card's mana value; and
3. Puts the discovered card to the player's hand if they choose not to cast it, instead of putting it alongside other exiled cards.

There are no cards with discover 1 or 2, making it harder to cast suspend spells with discover, such as Hypergenesis. Most cards with "discover N" use 3, 4, or 5 as the discover value, with some using discover X, and two cards use discover 10. As such, it could also go on cheaper spells and activated abilities, such as on lands, though most are still restricted by the mana spent. However, putting it on triggered abilities lets it chain with 3-mana clones, which got Geological Appraiser banned in Pioneer quickly.

Curator of Sun's Creation doubles Discover triggers.

Rules

From the glossary of the Comprehensive Rules (June 19, 2026—Marvel Super Heroes)

Discover

A keyword ability that may allow a player to cast a random spell for free. See rule 701.57, “Discover.”

From the Comprehensive Rules (June 19, 2026—Marvel Super Heroes)

• 701.57. Discover
  • 701.57a “Discover N” means “Exile cards from the top of your library until you exile a nonland card with mana value N or less. You may cast that card without paying its mana cost if the resulting spell’s mana value is less than or equal to N. If you don’t cast it, put that card into your hand. Put the remaining exiled cards on the bottom of your library in a random order.”
  • 701.57b A player has “discovered” after the process described in 701.57a is complete, even if some or all of those actions were impossible.
  • 701.57c If the final card exiled during the process described in rule 701.57a has mana value N or less, it is the “discovered card,” regardless of whether it was cast or put into a player’s hand.

Rulings

Rulings are informal clarifications of rule interactions. They may become outdated.

Informal rulings Rulings are informal clarifications of rule interactions. They may become outdated. “We are merely interpreters.”

From the Release Notes for The Lost Caverns of Ixalan (November 7, 2023)

• "Discover N" means "Exile cards from the top of your library until you exile a nonland card with mana value N or less. That card is the "discovered" card. You may cast that card without paying its mana cost if the resulting spell's mana value is less than or equal to N. If you don't cast it, put that card into your hand. Put the remaining exiled cards on the bottom of your library in a random order."
• A spell's mana value is determined only by its mana cost. Ignore any alternative costs, additional costs, cost increases, or cost reductions.
• When you discover, you must exile cards. The only optional part of the ability is whether you cast the exiled card or put it into your hand.
• You exile the cards face up. All players will be able to see them.
• If you cast a spell "without paying its mana cost", you can't choose to cast it for any alternative costs. You can, however, pay additional costs. If the spell has any mandatory additional costs, you must pay those to cast it.
• If the discovered card has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
• If you can't cast the discovered card (perhaps because there are no legal targets for the spell), you'll put it into your hand.
• Some spells and abilities that cause you to discover may require targets. If each target chosen is an illegal target as that spell or ability tries to resolve, it won't resolve, and you won't discover.
• The mana value of a split card is determined by the combined mana cost of its two halves. If discover allows you to cast a split card, you may cast either half (as long as its mana value is less than or equal to the effect's discover value) but not both halves.
• If you discover an adventurer card, split card, or modal double-faced card, you might be able to cast that card with either set of characteristics, depending on the effect's discover value. For example, if you discover 4 and reveal Galvanic Giant (an adventurer card from Wilds of Eldraine with a mana value of 4), you could cast Galvanic Giant, but not Storm Reading (its Adventure, which has a mana value of 7). If you discover 7 and reveal Galvanic Giant, you could cast either Galvanic Giant or Storm Reading.

Examples

Example

Geological Appraiser
Creature — Human Artificer
3/2
When this creature enters, if you cast it, discover 3. (Exile cards from the top of your library until you exile a nonland card with mana value 3 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)