Cheapest priced copy (Return to Ravnica): $0.49 at Card Kingdom, near mint, their price list as of .
Counterflux 
Instant · Rare · Secret Lair Drop · #2471
This spell can't be countered.
Counter target spell you don't control.
Overload {1}{U}{U}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $6.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2015 | 214 | Rare | $0.99 | — |
| Return to Ravnica | 153 | Rare | $0.49 | $3.99 |
| Secret Lair Drop | 482 | Rare | $2.49 | $1.79 |
| Secret Lair Drop | 2471 | Rare | $4.49 | $6.99 |
4 rulings from Wizards of the Coast
- 12 January 2024If you don't pay the overload cost of a spell with overload, that spell will have a single target. If you pay the overload cost, the spell won't have any targets.
- 12 January 2024If you are instructed to cast a spell with overload "without paying its mana cost," you can't choose to pay its overload cost instead.
- 12 January 2024Because a spell with overload doesn't target when its overload cost is paid, it may affect permanents with hexproof or with protection from the appropriate color.
- 12 January 2024To determine the total cost of a spell, start with the mana cost or alternative cost you're paying (such as an overload cost), add any cost increases, then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.