So the way this was worded initially made me think it is Zenos, since he’s been having dreams of the Final Days. Yet judging from the dialogue translated from the French version, I think it is indeed the tower (or more precisely, something embedded/held in it), and it is a living organic thing, with a shriek at the end. I wonder if this is Fandaniel’s [redacted]. Certainly, the "you know what" that he wants Zenos to control.
My supposition is that Fandaniel is incapable of creating the Final Days in exactly the same way, since sundered mortals lack the ancients’ unique capacity for creation magicks. With the clear dreams Zenos has of the Final Days, perhaps that has been embedded into whatever the structure is and is allowing Fandaniel to exploit this. By dreaming more, it can gather more aether, probably siphoning it as the towers do. Possibly requiring an act of control from Zenos to do it. Although gathering more aether by dreaming would appear inconsistent with a Primal, mayhap it would not be if it’s draining the land to fuel this dreaming and start the inception of the Terminus beasts. Fandaniel refers to the “gateway of the gods” being complete. Maybe a bit of embellishment but perhaps it is in relation to whatever he truly serves. It calls to mind the floating Zealaurot zone, although that could also tie into Sharlayan's plans in some manner. With the dreams plus Anima, as others have noted (and some pointed out
this as well) - the X refs do seem to be coming in thick and fast.)
The ability of his glyphs near the Confluences to sow chaos amongst the elements again reminds me of an aspect of the Final days,
detailed by Hyth. Whether this is a different method to how it was achieved in ancient times or not remains to be seen, though the Walls of the Forgotten has long had me suspicious in its resemblance to a Telotower (top
here and also
here). Perhaps they hid any such structures better back then. Either way it does look like the ultimate plan was to route all the aether back to Garlemald. We’ll see what more the towers are hiding.
They continue to each operate based on their own obsession; Fandaniel, to bring the end of all life, and Zenos to get the fight he wants and bait the MC, roiling with rage. Finally, we saw the moon take on its ominous reddish hue.
Even with the cure for tempering, some soldiers in the fight remain too far gone to rescue.