Jovik pours the oil liberally over the moss and mold on the wall, stepping back for a moment to survey his work. The smell of oil is sharp on the nose, and you are going to have to leave the room quickly once you set it alight due to the low ceilings and the volume of smoke.
The mold still holds its strange shape, looking, for once, like little more than a very bad damp patch.
Jovik steps forward and ignites the oil. The flames leap up quickly, catching and carrying across the wall, engulfing the entire mold patch with speed.
Smoke billows out as the oil quickly engulfs its fuel source, eating into the moss.
Then you hear it. A strange noise like a high pitched wail heard from afar. The noise grows, until the room vibrates with the sonic assault. You call cover your ears and start to move out of the room quickly. As you leave the room the horrible meal falls of the table with a squelch, shelves tumble from the walls, and two chairs topple.
Outside the room the smoke is leaking, leaving a tart odor in the air. Looking around at the various ghoul corpses littering the floor, as the chamber slowly fills with tendrils of smoke.
The wailing falls off, going quiet for a second. You can hear the crackle and hissing of the fire as it burns off wet patches. And then there is a single loud pop, like a jar exploding in a fire, from inside the room. After that there is just silence.
You move away from the room for a while, waiting for the fire to do its damage. When the smoke dies down, and eventually dissipates on the breeze that blows in from the pit, Danth walks towards the room and takes a look inside.
The wall has been scoured by fire. It is a black mess, but clear of the mold. Still, he can sense it, he can feel the remnant of evil here. Something remains. It is only his own unity with the divine that makes his sense it. It is weak. A damaged source of great evil, but still there. The fire has done its job, for now, but Danth knows that this place is not sanctified.