Remathilis
Legend
I like the mummy idea, another very dangerous but less up front deadly. There's a good chance anyone infected with rotting fist won't be able to get to a remove curse in time, though, as it's a 3rd level spell and that's 2 more levels of adventuring after Death House. You could give them to means to cast it a few times in some of the treasure in the house, though, scrolls and such.
I might have to toss a scroll of Remove Curse into a treasure pile somewhere. The big advantages are a.) its slow and they can outrun/evade him in melee. 2.) Its vulnerable to fire, which the cleric of light loves to use and 3.) Its got a heckuva lot less hp (even with resistance). The idea of being chased by this monster in the catacombs trying whittle it down with spells and ranged attacks should be terrifying enough (and the primary melee combatants have good Con saves; we might lose someone, but that's straight up better than the TPK that the SM is.
If they escape and still need a healer, there is always Jeny Greenteeth. :evil: