Cheapest priced copy (Forgotten Realms Commander): $0.59 at Card Kingdom, near mint, their price list as of .
Dead Man's Chest 
Enchantment — Aura · Rare · Rivals of Ixalan · #66
Enchant creature an opponent controls
When enchanted creature dies, exile cards equal to its power from the top of its owner's library. You may cast spells from among those cards for as long as they remain exiled, and mana of any type can be spent to cast them.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.59 to $2.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Forgotten Realms Commander | 97 | Rare | $0.59 | — |
| Rivals of Ixalan Promos | 66s | Rare | — | $2.29 |
| Rivals of Ixalan | 66 | Rare | $0.69 | $1.49 |
7 rulings from Wizards of the Coast
- 19 January 2018If you gain control of the enchanted creature, Dead Man's Chest will be put into your graveyard.
- 19 January 2018To determine how many cards to exile, use the enchanted creature's power as it last existed on the battlefield.
- 19 January 2018You are a creature's owner if the card representing it began the game in your deck, or if it's a token that entered the battlefield under your control. If Dead Man's Chest enchants a creature that you own but an opponent controls, you'll exile cards from your library.
- 19 January 2018The effect of Dead Man's Chest doesn't change when you can cast the exiled cards. For example, if you exile a creature card without flash, you can cast it only during your main phase when the stack is empty.
- 19 January 2018Casting an exiled card causes it to leave exile. You can't cast it multiple times.
- 19 January 2018If Dead Man's Chest and the enchanted creature are both put into graveyards at the same time, the last ability of Dead Man's Chest still triggers.
- 19 January 2018In a multiplayer game, if a player leaves the game, all cards that player owns leave as well. If you leave the game, any spells or permanents you control from Dead Man's Chest's ability are exiled.