You need some exercise, chubby cursed sprites.
In Firestorm Citadel depth 25, experienced parties often split up to clear rooms faster, and they would place the sprites right outside a room's force field to flag it as done.
And when all the rooms are cleared: the most tedious part of Firestorm Citadel. Bringing the cursed sprites back to the fountain.
With the exception of the fire/spike/wheel room in lower left, all other cursed sprites can be retrieved completely safe, as they are locked away until the enemies are gone. The only risk, really, is lagging into shadow fire as you run around.
So I propose a change: As soon as all cursed sprites are moved outside the force fields, they get purified automatically. They could either teleport to the fountain, or use their chubby little legs and walk there themselves.
Slags spawn every time a room is cleared while you bring the sprite to the fountain. You are supposed to avoid being killed by them while getting the sprite to the fountain. The fire on the way back to the fountain is also there to make it more difficult.