I am still running my library Dungeons & Dragons adventure of mutations and madness, which has led now to some interesting complications for my players and their characters.
I decided early on that any players who accumulated too many short-term madness effects would begin rolling instead on the long-term madness effects table. The short-term effects last mere minutes, but long-term effects take hours to pass. Indefinite effects only end with significant magical or divine intervention, and no one has crossed that threshold... yet...
One inquisitive character did get hit with some long-term madness in the form of an inability to speak, which impeded communication; and
hallucinations, which imposed disadvantage on ability checks. However, the party chose to fortify their position and try to rest for the duration of that madness, because another character had a really bad short-term madness roll.
You see, the paladin also went mad, and her result was a violent bloodrage seeing all nearby characters as enemies. I got to basically take a break as Dungeon Master because player vs. player combat was being run by the rest of the table with little input from me. They finally managed to knock out their party's juggernaut, but not before she took down another party member. Even after applying healing potions to restore hit points to both of them, it took time to recover consciousness.
Oh, and the potion they used was from the dubious high priest of the Radiant Church. Is it just a curative elixir, or will there be side effects? The table joke for today was when I suggested the deity of the Radiant Church was named Pfizer. I love sowing paranoia and suspicion. MWAHAHAHAHA!!!