One of the many demons born from the Chaos Flame, the Old Demon King is now among the last of the dying race still existing in the world. It resides in a large chamber surrounded by the corpses of Capra Demons and Stray Demons.
The Old Demon King was likely a high ranking demon that combated other demons in order to rise to the position as their new lord and master after the Bed of Chaos was destroyed.
Since he bears resemblance to the Demon mini-bosses fought previously, it is possible that the demons saw him as the strongest and most fit for leadership, or he simply bludgeoned his way up the ranks until none dared challenge his rule (this could be one reason for the corpses of demons within his chamber).
It is unclear what has happened prior to when the Ashen One fights the Old Demon King, but one can assume that with the multitude of dead demons within his chamber and the fact that the Bed of Chaos is destroyed, the age of demons is coming to an end; perhaps this is a result of Lorian battling the demon prince, a war that caused the majority of demons to die - and without the Chaos Flame, it is impossible for more demons to be "born" into the world. All that remains is in the small remnants of the Demon Ruins (presumably Lost Izalith). Locked in his chamber, old and dying, he remains here to fight for what little remains of his race.
Ultimately, the Ashen One comes forth and faces the Old Demon King. The king fights valiantly, but at the end of his final fight, his flame dies out and he collapses exhausted, helpless as the Ashen One finally strikes him down.
The Old Demon King is a fairly easy boss to fight, with a very predictable and well telegraphed attack pattern. It uses a great hammer to attack using melee or area of effect attacks. One of the best strategies for killing this boss is to stay very close to him to bait out one of his melee attacks. After he attacks, move in for a couple of strikes then back off because he is likely to do one of his area of effect attacks.
Caster builds should have little difficulty in defeating the King. Although he moves relatively quickly, it is fairly simple to keep your distance while firing off spells. Using the mounds of corpses for cover can be a helpful way to avoid damage while charging a spell.
In his second form, he will gain more fire damage per attack; however, this should not change your tactic.
It will cast a slow moving meteor shower attack that can be identified by the king waving his hammer in a circular motion in the air. To avoid this, simply run away from him. It will use its area of effect attack by holding its hammer vertically, then quickly raising it and letting it hit the ground. It does a fair amount of damage but can easily be avoided. He also has a fire breathing pyromancy and can summon a ring of fire that expands and contracts once inside the fight area. His pyromancies can be avoided entirely by running or rolling away from him.
Care should be taken while maneuvering around the boss, though, as the irregular shape of his body may prevent the player from moving as desired and instead get pushed around. In addition, one cannot pass through his legs in an attempt to make it to the other side.
Soul of the Old Demon King
- Weak against Black Knights' weaponry (Black Knight Sword, Black Knight Greatsword, Black Knight Greataxe, Black Knight Glaive).
- According to the item's description, the Old Demon King's great hammer is imbued with remnants of the Chaos Flame.
- The body of the Centipede Demon can be seen lying among the many demon corpses surrounding the boss arena.
- During the second phase of the fight, a slightly remixed excerpt of the Bed of Chaos's theme can be heard.
- If the Demon King is put to 10 percent health and left alone, he will promptly hesitate before causing an area-of-effect explosion of fire, which will put his flame out but leave him alive. He will drag himself toward the player and weakly swing his weapon until he is finished off.