It allows you to purchase a Radiant Aurite 1 time from a aurite location during a run. Radiant Aurite costs 777, and when used on a 3rd form monster, gives them the rest of the abilities you didnt pick when evolving them.
you shouldnt be able to, there is a small bug with that option allowing you to buy it even if you dont have the village station built though. There is one you can get from the greater blessings rewards from looping in infinite mode though. That one doesnt care if you bought one and doesnt require the village.