Chaos Moon is a rare Enchantment card from Ice Age (ICE), collector number 179. Current market price: $1.04, TCGplayer market prices via Scryfall.
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.