Ritual of Subdual is a rare Enchantment card from Ice Age (ICE), collector number 261. Current market price: $1.41, TCGplayer market prices via Scryfall.
Cumulative upkeep {2} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) If a land is tapped for mana, it produces colorless mana instead of any other type.