If you cant exileem, stealem
If you reveal a nonland card when a creature explores and leave it on top of your library, then the creature explores again immediately afterwards, you'll reveal the same card again
If in doubt, consult its official Gatherer database entry (the original printing is the first expansion listed), or its UnCommander card entry if it has one.
Typically selling for around $4 on average, this card is, once again, a true Commander staple
The best thing to do with this when you turn it face up is to help your creature dodge removal, but just rebuying ETBs, flipping disguised creatures, or getting rid of a problematic nonland permanent an opponent controls and giving them a detective instead makes this into a bit of a swiss army knife
The second allows the card to time travel three times as a sorcery at the cost of seven colourless mana