Ruins of the Immortal Warlord
Standing 100 feet off the shores of the vast Sapphire Lake are the ruins of a small fortress standing atop a rocky islet. The fortress belonged to a lich posing as a warlord from the Kingdom of Old Hagada, but fell rapidly into ruin when the Shrouded Hero was able to pierce the lich with the Blade of Five Seals. The lich cursed the assassin and his incompetent guards with his final breath. He cursed them to the same fate, their bodies petrifying and all of their souls being sealed in the Sheath of Five Seals. Afterwards, the warlord’s armies were defeated on the battlefield and the fortress became abandoned.
In this short 3rd level dungeon crawl, the party investigate a ruined island fortress to solve a mysterious puzzle box. You can run this as a one-shot or plop this into your campaign world with minimal effort. The adventure is designed for Shadowdark RPG and references the core rulebook. If you're an experienced game master, you could convert the adventure to whatever system you prefer.