The Soul of Cinder is an interesting boss because it has four distinct movesets and weapons, switching between each as the battle progresses.
This is the most basic version of the group, with sweeping sword attacks that are fairly easy to dodge. Stay at a medium distance from the Soul of Cinder and circle around to the right, rolling under any attacks that make you nervous, and then strike when he recovers.
The trick to this stage is to learn which attacks have a slow charge to them, meaning you’ll want to roll later, and be aggressive when he is recovering from his attacks.
This moveset is probably the easiest because you can hug the Soul of Cinder to avoid the majority of his spells.
There are only two spells you need to deal with in this stage: Homing Soulmass, which can easily be avoided by rolling when the orbs activate, and Soul Stream, which you can avoid by getting behind him and going all out during the long attack.
The curved blade offers the Soul of Cinder with quick attacks that are difficult to avoid, but they are much weaker than the attacks in other forms. Lure him to perform an attack and roll under them to strike or back off and use ranged attacks to get you through this aggressive stage.
The majority of attacks in this moveset are piercing attack or sweep attacks that are pretty easy to avoid if you stick close and roll. Strike after he does a heavy attack and you’ll get through this phase without a hitch, except possibly taking a Wrath of the Gods to the face.
When the Soul of Cinder reaches zero health he’ll pause and hold his sword at waist height before thrusting it into the ground in a huge explosion. This will refresh his health and he’ll enter a new moveset with a greatsword.
This is an extremely dangerous stage simply because of one move: a 5-hit combo that will juggle you in the air and tear through you health. Because this move will surely kill you, unless you’ve pumped a ton of points into Vitality, you’ll want to keep your distance from the Soul of Cinder and focus on using ranged attacks for the final stage.
Drops: 100,000 Souls , Soul of the Lords
Reach "To Link the First Flame" ending.
Reach "The End of Fire" ending.
Reach "The Usurpation of Fire" ending.
Congratulations for completing Dark Souls III