Cheapest priced copy (Ice Age): $1.29 at Card Kingdom, near mint, their price list as of .
Chaos Moon 
Enchantment · Rare · Ice Age · #179
At the beginning of each upkeep, count the number of permanents. If the number is odd, until end of turn, red creatures get +1/+1 and whenever a player taps a Mountain for mana, that player adds an additional {R}. If the number is even, until end of turn, red creatures get -1/-1 and if a player taps a Mountain for mana, that Mountain produces colorless mana instead of any other type.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $1.29 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ice Age | 179 | Rare | $1.29 | — |
One ruling from Wizards of the Coast
- 1 May 2006In Two-Headed Giant, triggers only once per upkeep, not once for each player.