Wizard's Isle (5E)

From the introduction: Millennia ago, the powerful archmage Seldorius of Farland built for himself on Hamor Island a compound and fortress where he could do his research undisturbed, and where he could found a council of wise people to combat evil in the world. This was the second Cadre of the Wise. Eventually they interfered with the dreaded Dweller in the Wintervale, a powerful evil personage. User summary: For 19th - 20th level characters.