Cheapest priced copy (Duel Decks: Heroes vs. Monsters): $0.49 at Card Kingdom, near mint, their price list as of .
Conquering Manticore 
Creature — Manticore · 5/5 · Rare · Rise of the Eldrazi · #139
Flying
When this creature enters, gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.49 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Heroes vs. Monsters | 55 | Rare | $0.49 | — |
| Rise of the Eldrazi | 139 | Rare | $0.49 | $0.79 |
2 rulings from Wizards of the Coast
- 15 June 2010You retain control of the affected creature until end of turn, even if you lose control of Conquering Manticore before then.
- 15 June 2010You may target a creature that’s already untapped.