Seeing the familiar view, Lucien immediately recalled the identity of the sphinx mummy before him. It was exactly Finks, the King of Sphinxes that he encountered when he accomplished Rhine's task.
At that time, it was sealed inside a coffin, and it was executed by him with Pale Justice after his resurrection, falling into dormancy again. When he escaped through the gap of the World of Souls, he saw the shadow of its mausoleum, the bloodstained ball of light, and the weird red 'spider threads', which made him realize that it was actually sealed in the World of Souls.
Right now, its real self had been slain by the Sword of Truth through the projection. There was no need to worry about sealing him anymore, because beings which had completely died could not be sealed.