The Green Knight really said: yes this is a retelling of Arthurian poetry but we are going to lay out a full process of cyclical ego death for our Unlikely Hero because all Hero Myths are about ego death in Leary's description of ego death in The Psychedelic Experience, he essentially lays out three parts:
1. ego loss, or a game leading to transience of the self
2. a period of hallucination or discovery
3. the return to routine game reality and selfhood