Cheapest priced copy (Commander 2021): $0.49 at Card Kingdom, near mint, their price list as of .
Muse Vortex 
Sorcery · Rare · Commander 2021 · #28
Exile the top X cards of your library. You may cast an instant or sorcery spell with mana value X or less from among them without paying its mana cost. Then put the exiled instant and sorcery cards that weren't cast this way into your hand and the rest on the bottom of your library in a random order.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2021 | 28 | Rare | $0.49 | — |
| Commander 2021 | 355 | Rare | $0.49 | — |
2 rulings from Wizards of the Coast
- 16 April 2021If you cast a spell with {X} in its cost without paying its mana cost, you must choose 0 as the value of X.
- 16 April 2021You don’t have to cast an instant or sorcery spell this way. If you don’t, all exiled instant or sorcery cards will be put into your hand.