Cheapest priced copy (Born of the Gods): $0.69 at Card Kingdom, near mint, their price list as of .
Arbiter of the Ideal 
Creature — Sphinx · 4/5 · Rare · Born of the Gods · #31
Flying
Inspired — Whenever this creature becomes untapped, reveal the top card of your library. If it's an artifact, creature, or land card, you may put it onto the battlefield with a manifestation counter on it. That permanent is an enchantment in addition to its other types.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.69 to $1.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Born of the Gods | 31 | Rare | $0.69 | $0.99 |
| Born of the Gods Promos | 31★ | Rare | — | $1.29 |
7 rulings from Wizards of the Coast
- 1 February 2014If an inspired ability triggers during your untap step, the ability will be put on the stack at the beginning of your upkeep. If the ability creates one or more token creatures, those creatures won’t be able to attack that turn (unless they gain haste).
- 1 February 2014The permanent will be an enchantment as it enters the battlefield and will cause constellation abilities of permanents you control to trigger.
- 1 February 2014Inspired abilities don’t trigger when the creature enters the battlefield.
- 1 February 2014If the inspired ability includes an optional cost, you decide whether to pay that cost as the ability resolves. You can do this even if the creature leaves the battlefield in response to the ability.
- 1 February 2014If you choose to not put the card onto the battlefield, or if the card isn’t one of the listed types, it will remain on top of your library. (Note that revealing the card is not optional.)
- 1 February 2014The manifestation counter is a memory aid only. The permanent will continue to be an enchantment in addition to its other types even if that counter is removed.
- 1 February 2014Inspired abilities trigger no matter how the creature becomes untapped: by the turn-based action at the beginning of the untap step or by a spell or ability.