Khoiak 23rd November was a somber celebration to mark the completion the first season (Akhet) and was later associated with the death of Osiris. However, it was followed very closely on 29th November by Nehebkau which marked the start of the next season Peret. This came to be seen as a kind of death and rebirth process.

Nehebkau, 29th November

Literally meant 'he who unites the Kas'; the Ka being what we would interpret as spirit or soul. The Egyptians believed he was an original primeval god. He was linked to the primeval waters before creation and bound to the sun god at the beginning of time. He was depicted in the form of a snake with arms and legs and occasionally wings! He was the god of protection who guarded both in life and death. He was also associated with protection and magic.  

“Homage to thee, Netethib, daughter of these four gods who are in the Great House. Even when the command of Unas goes not forth, uncover yourselves in order that Unas may see you as Horus seeth Isis, as Nehebkau seeth Serqet, as Sobek seeth Nit, and as Set seeth Netethib”.  -- Pyramid Text of Unas