The Shade Isle Campaign
The Soul-Still was an unholy artifact created by the Church of Acrefatum. Large enough to fill a room, it consisted of a huge vat of glowing green ectoplasm and tortured human souls, attached by tubes and pipes and wires to magically-operated control-panels and forges. The purpose of this infernal machine was to render these souls down into magical crystals called mana stones.
The adventuring company destroyed the Soul-Still by rerouting its many tubes and pipes, causing pressure to build within the vat until it blew. The resulting explosion destroyed approximately a third of the uppermost level of Shade Abbey, the Keep of the Soul-Still.