Cheapest priced copy (Odyssey): $0.59 at Card Kingdom, near mint, their price list as of .
Shifty Doppelganger 
Creature — Shapeshifter · 1/1 · Rare · Odyssey · #101
{3}{U}, Exile this creature: You may put a creature card from your hand onto the battlefield. If you do, that creature gains haste until end of turn. At the beginning of the next end step, sacrifice that creature. If you do, return this card to the battlefield.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.59 to $4.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Odyssey | 101 | Rare | $0.59 | $4.49 |
3 rulings from Wizards of the Coast
- 4 October 2004If the creature is not still on the battlefield at beginning of the End step, then you do not return this card to the battlefield.
- 1 May 2007Putting the card onto the battlefield is optional. When the ability resolves, you can choose not to.
- 1 August 2008This card has received errata such that putting a creature card from your hand onto the battlefield is now optional. This means you no longer need a third-party to verify that you don't have any creature cards in your hand if you don't put something onto the battlefield.