Chaos Flame Ember - Dark Souls

Chaos Flame Ember

Ember required for weapon ascension. Chaos Flame Ember is an art of the lost city of Izalith. Handled only by blacksmiths knowledgeable in ancient methods. Ascends +5 fire weapon to chaos weapon. (chaos weapon can be reinforced to +5) Chaos weapons are demon weapons augmented by humanity which inflict fire damage

Chaos Flame Ember is an Ember in Dark Souls.

Found after beating Ceaseless Discharge, which is located right after the boss in Blighttown, Chaos Witch Quelaag.
After you kill him, the lava will harden allowing you to walk to the area he was standing. The Ember is located in a pool of lava (not the item against the rock-wall), and is guarded by 7-8 or so Taurus Demons, so you better take them on one at a time.
Use of the Flame Stoneplate Ring and the Flash Sweat spell is recomended, because you'll actually have to walk through the lava to get to the Ember. Also, the Gold-Hemmed Robe set provides great fire resistance, and can be looted from a corpse near Ceaseless Discharge.
The Orange Charred Ring, dropped by the Centipede Demon, can be used to safely acquire the Ember.
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Chaos weapons cannot be buffed.
Chaos weapons will inflict damage depending on your Humanity level (max at 10 Humanity). The Humanity scaling decreases exponentially: the first humanity is worth more damage than the tenth. Bear this in mind.
Chaos ascension also changes the fire damage to physical damage ratio; from 1:1 to approx 2:1.
Exploiting the Dark Hand's R2 attack can give you a lot of soft Humanity, if you're worried about using up your reserves.