Cuttlefish That Loves Diving
So this is like a Snake of Mercury: Reboot but on much higher scale. And since Lumian remembers the past it seems like this is the first loop or he remembers this loop because he became a beyonder in this loop? Also the condition of reboot is also not clear but the symbol of thorny chains is related to Fate pathway is clear. CoI is probably a neighboring GOO to Key of Light.
I wonder why the name of the book is an outer god name. oh btw, now that I think about it. in the last meeting of tarot club Klein commissioned xio to find about the beyonder characteristic of red priest pathway, can it be he already see that Lumian will be the next great old ones? oh yeah kinda spoiler the name of above the sequence for red priest is 'city of destruction' and it highly likely that the ruin in Lumian dream is red priest sefirot called 'city of calamity'
Is most likely a time loop if you considers what happened in the series so far makes sense if you consider it a time loop and name of this volume is nightmare as time loop gives off nightmare feel, also considering padre beyonder abilities being similar to the wheel of fortune pathway; while padre pathway seems not be part of 22 pathways and is likely a new pathway that is connected to circle of inevitability.
it's a loop but only restricted to the town so when the letter for help was sent it became outside the loop but the person who sent it still in the loop and all his memory are rebooted . it is the power of fate from COI to recontrol the protagonist against interference from the fool to help him that's why he can remember as he explored the dream and strenthened his connection with the fool