Cheapest priced copy (Portal Three Kingdoms): $42.99 at Card Kingdom, near mint, their price list as of .
Eightfold Maze 
Instant · Rare · Portal Three Kingdoms · #2
Cast this spell only during the declare attackers step and only if you've been attacked this step.
Destroy target attacking creature.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $42.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Portal Three Kingdoms | 2 | Rare | $42.99 | — |
2 rulings from Wizards of the Coast
- 1 October 2009If all the attacking creatures attack your planeswalkers, you can’t cast Eightfold Maze. To cast it, a creature needs to have attacked _you_.
- 1 October 2009If you’re able to cast Eightfold Maze, it can target any attacking creature (including one attacking a planeswalker).