Crystal Quarry

Five generic plus a tap to produce one of every color in a single activation: that is the bargain this land makes, and it is built for exactly one kind of deck. The first ability is a plain colorless source, keeping the card from sitting dead when you simply need a source that turns sideways and produces mana. The second is the reason it exists, and it is priced as a conversion engine rather than a fixer. The rate is awful if all you want is to splash a color: nobody pays five and a tap to cast a two-color spell. The rate is exactly right if your deck is drowning in generic and colorless mana but starved for the colored requirements to spend it. That is the inversion at the heart of the card. Most fixing lands assume you have plenty of mana and treat color as the scarce resource, doling out one or two specific pips. Crystal Quarry assumes the opposite: that quantity is solved (by ramp, by mana rocks, by big lands) and that the missing piece is breadth of color. It takes a surplus of undifferentiated mana and filters it into the full rainbow at once, so a five-color payoff that needs WUBRG on a single turn has somewhere to draw from. The colorless mode is the floor that keeps it honest; the rainbow mode is the only reason to run it.