So many cool options, so few to choose! I guess a downside with being a Mathilde level Important Person is that there's so many interesting stuff you could do and only so much hours in a day. In the end I'll go with:
[X] Orb Reveal
[X] Silk
Because we've been waiting for this a long, long time, and I absolutely don't want to miss it. Especially the Gigaflex, I can't wait to see Algard's and Dragomas' faces. And headpats, lots of headpats.
[X] Lord Seilph, the Mystic
Because it's not every day you get to chat with a Grey Lord (well, for Mathilde it kinda is, but not outside of work business), or when you get to chat about questionable magic with anyone in general. Both at once is a really unique opportunity.
[X] Pan's Treehouse
Because Panoramia.
[X] Karak Vlag books
Because B Ö Ö K, and also lots of magical lore. Fire Spire books are always juicy, but potential Runesmith perspectives on Wind Magic on top of that? Or, even, on how to wield Wind Magic? Truly fascinating.
Honorable mention to: the Nehekhara books, only slightly less interesting than the Vlag ones; Sarvoi, because I'd love talking about Apparitions with our favorite magic nerd Elf; the Druchii, to fuck over Karond Kar; and the Skull River Ambush because it's been so long already and I still want to know What The Hell Was All That About and whether the Slaaneshi Cult in Marienburg really was involved.