Cheapest priced copy (Dragon's Maze): $0.35 at Card Kingdom, near mint, their price list as of .
Nivix Cyclops 
Creature — Cyclops · 1/4 · Common · Duel Decks: Mind vs. Might · #24
Defender
Whenever you cast an instant or sorcery spell, this creature gets +3/+0 until end of turn and can attack this turn as though it didn't have defender.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
2 printings · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Mind vs. Might | 24 | Common | $0.39 | — |
| Dragon's Maze | 87 | Common | $0.35 | $0.79 |
One ruling from Wizards of the Coast
- 15 April 2013Nivix Cyclops still has defender after its triggered ability resolves, although it will be able to attack.