I do not mean Maclaine's version- that was used for A Bug in the System trailer- which is amazing, but I mean Asja Kadric's version.
The idea behind it is to balance this season with some hope and happiness, even if the present times don't show it at all (something like in the trailer for episode 4).
Daybreak's trailer had this deep and sad music in it.
A Bug in the System had this mix of this jokey aspect of the story and then they showed how creepy the story can go.
Long Live the Lich continued the series of creepy, scaraby-like music (I'm talking about the first part of the trailer- not the music during the showing off the content and the mount).
A Star to Guide Us had Aurene's Theme to later show it's total opposite in the episode. (I still think The Calm before the Storm would fit better for the last episode, especially after playing the episode.)- I mean the track during Aurene's vision.
BTW I speculate that we'll return to the story of Sylvari in the next episode.
Certainly Caithe visited the Pale Tree once more while she was chasing after Aurene. We found out about the Egg from... the Pale Tree so the story kind of make a loop to the very beginning, when we saw the vision in the Dragon's Reach: part 2.
I'm also very curious about Canach's absence in A Star to Guide Us. It was also very weird- there was no sign he wouldn't appear after Episode 3. And Canach's name was never mentioned in the last episode.
It's unclear Caithe was following after us for a long time. But I think if she would, then she would certainly appear when Snaff and Eir appeared out of sudden- 100% sure.
Caithe also said: "The priestess was right, you do need better security", she alluded to the words Zafirah said: "You need better security" at the beginning of the last chapter.
She was at the Sun's Refuge when we reignited Balthazar's Sword, she wasn't in the Mists for sure, too. Because Glint would certainly point her out.
Anyway I think she didn't mean that SHE will help, but that she can help us find a clue. And I think she wants us to meet the Pale Tree.