The Mercury Lighthouse is located east of Imil and is the first Lighthouse you will encounter. Like all the lighthouses, it takes a certain kind of adept to open it. In this case, that adept is a Mercury Adept, more specifically, Mia. This Lighthouse offers the first "actual" story boss in the game. Mercury Lighthouse is filled to the brim with water and ice, which make it pretty hard to maneuver through. You don't need to do a lot of back tracking, but you do some. You must move pipers in the right order to allow water flow into certain areas to be able to pass, freezing water to move across it, and even walk across water at some points.
The boss that this certain lighthouse holds is Saturos alone in battle. With the aid of Mia and her healing psynergy, this fight shouldn't be hard at your levels. His attacks will be weakened because of the Mercury Lighthouse's effect on Mars psynergy, but he's still pretty tough.
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