Cheapest priced copy (Oath of the Gatewatch): $1.29 at Card Kingdom, near mint, their price list as of .
Crush of Tentacles 
Sorcery · Mythic · Oath of the Gatewatch · #53
Surge {3}{U}{U} (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
Return all nonland permanents to their owners' hands. If this spell's surge cost was paid, create an 8/8 blue Octopus creature token.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $1.29 to $5.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Oath of the Gatewatch | 53 | Mythic | $1.29 | $2.49 |
| Oath of the Gatewatch Promos | 53s | Mythic | — | $5.49 |
5 rulings from Wizards of the Coast
- 22 January 2016All other nonland permanents will already be in their owners' hands by the time the Octopus token is created. Any triggered abilities or abilities that would have otherwise affected that Octopus won't be around to matter.
- 22 January 2016Casting a spell for its surge cost doesn't change its mana cost or its mana value.
- 22 January 2016The other spell that you or a teammate cast can be one that's resolved, one that was countered, or (for instants with surge) one that's still on the stack.
- 22 January 2016If an instant or sorcery spell cast for its surge cost is copied, the copy is also considered to have had its surge cost paid.
- 22 January 2016For some cards, surge represents only an alternative cost, a discount that applies if you or a teammate has cast another spell this turn. Other cards, like Reckless Bushwhacker, have additional abilities or effects if you paid the surge cost to cast the spell.