Cheapest priced copy (Doctor Who): $0.59 at Card Kingdom, near mint, their price list as of .
Impending Flux 
Sorcery · Rare · Doctor Who · #386
Paradox — Impending Flux deals X damage to each opponent and each creature they control, where X is 1 plus the number of spells you've cast from anywhere other than your hand this turn.
Foretell {1}{R}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
4 printings · $0.59 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Doctor Who | 87 | Rare | $0.59 | $0.79 |
| Doctor Who | 386 | Rare | $1.79 | $1.99 |
| Doctor Who | 692 | Rare | — | $1.99 |
| Doctor Who | 977 | Rare | — | $2.99 |
7 rulings from Wizards of the Coast
- 13 October 2023If you cast Impending Flux from exile, it counts itself when determining the value of X.
- 13 October 2023Because exiling a card with foretell from your hand is a special action, you can do so any time you have priority during your turn, including in response to spells and abilities. Once you announce you're taking the action, no other player can respond by trying to remove the card from your hand.
- 13 October 2023Casting a foretold card from exile follows the timing rules for that card. If you foretell an instant card, you can cast it as soon as the next player's turn. In most cases, if you foretell a card that isn't an instant (like Impending Flux), you'll have to wait until your next turn to cast it.
- 13 October 2023Paradox abilities count any spells cast from zones other than your hand. These are usually spells cast from exile, the graveyard, or the command zone. They also count spells cast from outside the game, such as spells cast with Wish or Garth One-Eye's ability.
- 13 October 2023An instant or sorcery that counts how many spells you've cast from anywhere other than your hand, such as Surge of Brilliance, counts itself if it was cast from a zone other than your hand.
- 13 October 2023If a spell or ability allows you to copy a spell on the stack but doesn't specify that the spell is cast, that spell wasn't cast and won't be counted by paradox abilities. However, if a spell or ability allows you to cast a copy of a spell, that spell will be counted for paradox abilities.
- 13 October 2023A triggered ability that triggers when a spell is cast from anywhere other than your hand, such as that of The Thirteenth Doctor, functions only on the battlefield, so it doesn't trigger when you cast that spell from a zone other than your hand.