Cheapest priced copy (Duel Decks: Knights vs. Dragons): $0.35 at Card Kingdom, near mint, their price list as of .
Temporary Insanity 
Instant · Uncommon · Duel Decks: Knights vs. Dragons · #73
Untap target creature with power less than the number of cards in your graveyard and gain control of it until end of turn. That creature gains haste until end of turn.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Knights vs. Dragons | 73 | Uncommon | $0.35 | — |
| Torment | 116 | Uncommon | $0.35 | $0.79 |