I. FLIPPED. MY. ****. When Valka mentioned the Titans in the first few scenes. I was hoping it was going to be about either the Titans or another Magister trying to start some **** with the surface. (Namely, lodging open the Old God under the Waking Sea.)
I tip my tin-foil hat to everyone who contributed to the 'Titan's Blood is Lyrium', especially since we had, like, what, two lines referring to that in all of Dragon Age?
I've seen a lot of people criticize the lack of answers, and I can kinda understand that gripe. I feel like The Descent provides answers by assumption, if that makes sense. We've been handed a downright titanic piece of the puzzle, and can now focus on the theories that incorporate what we've learned.
While we didn't see Sandal, we now know of a very possible answer to his oddities. His 'Not Enchantment' look to be a higher-tier version of Valka's spellwork, and the prophecy could be the Titan providing some answers.
I spit on the IGN review or anyone else who claims that the DLC's environments are claustrophobic and/or samey. Some of Bioware's best level design I've seen in quite awhile. Varied, gorgeous environments. The top levels were the Deep Roads in HD glory, and the lower ones were exquisite.
I was disappointed that we couldn't speak to the Sha-Brytol. Apparently it's hinted that a king made contact with a Titan and wanted to uncover it and speak to it more, so he had his thaig dig too deep and sent them crashing down into the depths. *shrug* It was interesting that they were just parasites. Also interesting that they seem to subsist entirely on lyrium, and I'm kind of worried Valka will do the same. They match the description of 'The Pillars of the Earth' Codex, which would make them the 'proto-darkspawn' I kept going on about. If it suggests that Titans generally make the dwarves mindless like this, with the Shapers remaining sapient, I worry. Maybe that's why they went to sleep? To give the dwarves a chance to grow? What the hell happened that made all of the ancients fall apart at once? I doubt it was so simple as civil war among the Creators and the Forgotten Ones.
How do we figure the Titans fit into the Fade? Lyrium is consistently referred to as the 'essence of the Fade, and of magic', as the 'tears of the Fade', being able to help ones get into the Fade, but it also helps Templars and dwarves connect to the Titans, which keeps magic from getting in. Doesn't Cole suggest that the Titans are 'older' than the Fade? Or am I not remembering his dialogue properly?
The implications of the Titans being under the Deep Roads and having this kind of influence is rife with ramifications. The Primeval Thaig remains mysterious, however. It has both the Claws of Dumat and a design similar to the Titan levels. A lot of the lyrium is corrupted, suggesting that it's a Blighted Titan. Dwarves became mini-Guardians/rock wraiths, the Profane, by eating red lyrium, their gods'. Almost like proto-golems, which fits nicely with my adapted pet theory that the Titans approached Caridin in dreams and drove him to create the Anvil of the Void.
I saw one fan theory recently, I forget where (was it one of you guys?
) that suggests that the Temple of Sacred Ashes, Skyhold, and what's presumably the rest of the 'Sacred Mountains' of the Creators are built around slain Titans. Assuming that some Titans lived closer to the surface than others. (I guess that there's probably ones under most major dwarven cities.)
Malvernis (the 'demon' of pestilence in Legacy, that corrupts the Stone) becomes much more interesting with all of this context. And by interesting, I mean bewildering and annoying. 
How about those Scaled Ones, eh? Pre-Blight, and matching the lizard man drawing in the Temple of Mythal. Possibly Kossith, possibly dragonkin, possibly really devoted Reavers, possibly an entirely different race...Creepy, though.
Why is it that the words, "I ship them!" inevitably doom at least half of the couple? I had just finished saying how much I liked Valka and Renn, as a couple or as besties, when the Sha-Brytol gunners came a knocking.
Rest in peace, Jedi Knight Renn.
In non-DLC news, I finally noticed that the 'Thelm Golden-Handed' Codex entry is right next to the drawing of a giant green bear (Dirthamen's symbol being the bear, yes?) and what's probably Ghilan'nain.
I can be a bit slow.
And those are my lore impressions vomited onto the page. 