A Free Adventure by Simon Forster
Once upon a time there was a demon who ravaged the land. It was eventually stopped by the combined forces of the Holy Order of the First Blade, but proved unkillable. Instead, one of the Order, a priestess by name of Lucy, crafted a cage for the demon and trapped it. The demon-cage was then placed inside a purpose-built prison, and Lucy was made a Saint for her triumph.
That was centuries ago. The prison, for many decades, was maintained by jailors of the Order, but during the Holy Wars of the Snail Lords, the Order was decimated and over time simply faded away.
Then, for a time, the prison was abandoned save for the odd vermin that managed to creep inside; and throughout all that time, the demon raged inside its cage, trapped and undying.
This is a free adventure for you to use. Written using the ACKS rules, but compatible with similar games.