Soul of Cinder is the final boss of Dark Souls 3, he is the amalgamation of all The Lords of Cinder, which includes all the souls of The Chosen Undead, Lord Gwyn and possibly The Bearer of the Curse and Solaire.
When the Ashen One managed to reach the Kiln of the First Flame, he pulled his Coiled Sword and challenged the latter into a final deadly fight.
In order to protect the first flame, the Soul of Cinder used all the attacks and abilities at his disposal, including even the ones of Lord Gwyn, however they were not enough to stop the Ashen One, who was able to overcome and kill him.
The Soul of Cinders is extremely similar in appearance to The Chosen Undead, but more tall and menacing.
Power and Abilities
As the fusion of countless warriors the Soul of Cinder is regarded as the second strongest character of the series, he is able to use magic and manipulate fire and lightning at his will, he is also able to switch with all the classes considering the large amount of souls that forms his being.