Mythic rare is a rarity level, one step higher than rare. It is indicated by an orange-red colored expansion symbol, which originally was meant to provide a "fiery" appearance. The rarity was created for Shards of Alara, as some of the rares in that set were considered to be on a higher level than most of the other rares.
In general, 15 mythic rare cards appear in large sets and 10 appear in smaller sets, not counting on mythic rares exclusive in non-draft booster products. The most well-known mythic card type is that of the Planeswalker, which nearly always appear as mythic rares after Shards of Alara introduced them. These numbers differ on certain sets; notably in sets with a double-faced print sheet. This is due to the sheet having all rarities on a single sheet, so it has its own share of mythics, which varies from zero (Ixalan) to five (a cycle). Maze's End also got this treatment as the land-slot in Dragon's Maze, Mascot Exhibition for Lessons in Strixhaven: School of Mages, and Nicol Bolas, the Ravager got its own sheet in Core Set 2019. Oath of the Gatewatch expanded the typically small set Mythic count to 12 until they were discontinued after Rivals of Ixalan. Some supplemental draft sets (Ultimate Masters and Double Masters) have more than 15.
With the release of Dungeons & Dragons: Adventures in the Forgotten Realms, non-DFC mythic rares in normal distribution sets are upped to 20 per set.
Starting with Zendikar Rising booster packs, 1 in every 7.4 booster packs contain a mythic rare instead of a rare card. Before this set, about 1 in every 8 booster packs contain a mythic rare. Any given mythic is exactly twice as rare as any given rare due to the smaller pool of mythic rares versus rares, and they are printed on the same print sheet.
In non-booster sets
In the more recent Duel Decks, the "flagship" cards appeared as mythic rares, like Jace Beleren vs. Chandra Nalaar. The Premium Deck Series: Slivers had a single mythic rare of Sliver Overlord. Finally, each of the cards in the From the Vault sets are printed with a mythic rare expansion symbol, regardless of the card's original rarity.
- Mark Rosewater, Drive to Work #214 "2008"
- Wizards of the Coast (June 2, 2008). "Changes as of Shards of Alara". magicthegathering.com. Wizards of the Coast.
- Mark Rosewater (June 2, 2008). "The Year of Living Changerously". magicthegathering.com. Wizards of the Coast.
- Mark Rosewater (August 05, 2013). "Twenty Things That Were Going To Kill Magic". magicthegathering.com. Wizards of the Coast.
- Mark Rosewater (March 12, 2018). "Quite the Rarity". magicthegathering.com. Wizards of the Coast.
- Mark Rosewater (July 25, 2020). "Set Boosters". magicthegathering.com. Wizards of the Coast.