Daemon's fourth fight takes place in the Temple of the One during the Good Main Quest
Daemon will become invincible and summon acolytes. Kill them before the timer runs out or they will heal him. He will blink around the room, and use flame strike
He also turns invisible this fight, so have an item with true sight or just set up campfires with the Hunting ability. When he reaches critical health, he will summon a horde of powerful Demon Raiders
He will sometimes accidentally leave the Temple of the One. If he does, search for him on the symbol in the Northern Desert
(6.29): He has the items from 2:nd and 3:rd fight wich makes him drop the items he is suposed to have (King Daemonic's Set, Eternal, Gem of Eternity, Ultimate Orb of Evil, Demon Cuirass of Power, Demon Gauntlets of Strength).
You can pick up these items, however do note that they do not belong to your hero and will be dropped when attempting to save with them equipped.