Cheapest priced copy (Planar Chaos): $0.35 at Card Kingdom, near mint, their price list as of .
Circle of Affliction 
Enchantment · Uncommon · Planar Chaos · #66
As this enchantment enters, choose a color.
Whenever a source of the chosen color deals damage to you, you may pay {1}. If you do, target player loses 1 life and you gain 1 life.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Planar Chaos | 66 | Uncommon | $0.35 | $0.79 |
4 rulings from Wizards of the Coast
- 1 February 2007The player you target doesn’t have to be the controller of the source that dealt damage to you.
- 1 February 2007If several sources deal damage to you simultaneously (for example, several attacking creatures), this ability triggers once for each source.
- 1 February 2007If the damage reduces you to 0 or less life, you lose the game before Circle of Affliction’s ability has a chance to give you life.
- 1 February 2007Each time a source deals damage to you, you may pay {1}. You can’t pay more than {1}, even if more than 1 damage was dealt.