The Cerulean Amber Medallion +2 is a talisman you ... of the Site of Grace to reach the channel below, then explore the zone to find a coffin that will take you to a zone with a bossfight, this ...

This boss is hidden in the southernmost part of the map, near the Cerulean Coast Site of Grace. This can be found through the Ellac River Cave ... You'll reach this zone by getting to The Fissure ...