With a fully refreshed Estus Flask, I took the lift back down into the Abyss (thank you whoever built that) and made the rather trivial journey to the bottom where I faced
The captive Princess Dusk was here, so I set her free and we both warped out back to the shrine with Elizabeth. The thankful shroom gave me pieces of her to eat (eww), so I just politely said you're welcome and warped back to Firelink Shrine. Frampt was awake now so I got him to take me to the temple underneath where I used the lord souls to open the door to an ash blasted landscape at the center of which stood the Kiln of the First Flame. Frampt urged me on, instructing me to "link the fire" to end this age of undeath.
A handful of familiar nameless knights guarded the path to it, but couldn't stop me from reaching it. Indeed, the best defense the Kiln had was King Gwyn, the Lord of Cinder himself and with his giant flaming sword I became shishkebab really quick. Gave it a few more tries but the end result was the same. Deciding I needed to level up a bit more I left him there for the time being for some more bonfire jumping to see if I missed anything.
Damned overcompensating fire sword...