Cheapest priced copy (Ravnica: Clue Edition): $0.35 at Card Kingdom, near mint, their price list as of .
Rescuer Sphinx 
Creature — Sphinx · 3/2 · Uncommon · War of the Spark · #65
Flying
As this creature enters, you may return a nonland permanent you control to its owner's hand. If you do, this creature enters with a +1/+1 counter on it.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica: Clue Edition | 95 | Uncommon | $0.35 | — |
| War of the Spark | 65 | Uncommon | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 3 May 2019If Rescuer Sphinx somehow enters the battlefield at the same time as another permanent, you can’t return that permanent. You may choose only permanents that are already on the battlefield.
- 3 May 2019If the returned permanent had an ability that would otherwise have triggered when Rescuer Sphinx enters the battlefield (such as that of Kronch Wrangler), that ability won’t trigger.
- 3 May 2019You choose whether to return a nonland permanent and which one to return for Rescuer Sphinx’s ability while it’s entering the battlefield. No player may take actions between the time you choose which permanent to return and the time Rescuer Sphinx is on the battlefield with a +1/+1 counter.