Originally Posted by
Jokubas
The titan thing, as mentioned, is an obvious one. Considering that whole section seemed to exist to explain how Wrathion got that vision and the whole "We must rebuild the final titan" quote, it seemed pretty explicit that the titan souls were on Azeroth. It also made it explicit how the titan's souls escaped, and how Sargeras absolutely had no idea it happened. There are ways to interpret the new lore as an expansion and continuation of that, but it still contradicts it as written.
The Chronicle also said that Sargeras recruited the eredar because he needed leaders to command the Legion, and that demons respawned naturally if killed outside the Nether or an otherwise heavily fel-saturated location. I don't know if the former is being contradicted directly, but since the latter concept is being replaced with the idea that the world-soul of Argus is what allows the Legion to respawn, it heavily implies that Argus was only important due to its world-soul, and not its people.
There's also the relationship between Odyn, Helya, and the val'kyr. In the Chronicle, Odyn was offended by the dragons being empowered when perfectly good defenders like him already existed, and decided to invent the val'kyr as his own army to prove that he could do it without the dragons. The val'kyr needed to be undead, however, and no one wanted to volunteer for that, so he forced people into it. Loken gave Helya a way out and she and the val'kyr eventually broke free and betrayed Odyn. In Legion, Odyn was always charged with creating an army and formed an army of Light val'kyr, which everyone seems to see as an honor to become. Loken sowed discord between Odyn and Helya, leading her to betray him and eventually forcing her to create the kvaldir to imitate Odyn, since it seems most of the val'kyr stayed with him instead of her. In fact, val'kyr didn't show up around Helya at all in Legion until the raid in 7.1, despite her having all of them (except the Spirit Healers) in the Chronicle, leading me to believe they realized the contradiction and tried to offset it at least a little.
I think a subtle but telling sign of this difference is that in the Chronicle, Helya is a victim all the way, even if she falls in with the wrong crowd due to it. In Legion, Helya is gleeful about her malice, and never once tries to justify her hatred of Odyn despite it being extremely understandable in the Chronicle. The closest she ever comes to anything resembling saying anything bad about Odyn outside of generic insults is "He... must not... win...", which anyone would say about their nemesis. Likewise, Xal'atath has comments about how Odyn's arrogance helped convince Helya to betray him, not the much more blatant fact that he murdered her and forced a curse upon her like in the Chronicle.
The naaru are already on their way to being contradicted. The Chronicle describes them as just another lifeform that came into being naturally as Light exploded into the new universe. However, with the introduction of Prime Naaru, the idea that Elune (whoever she is) might have consciously created the Prime Naaru, and that Xe'ra may not be quite what she seems, are already setting up a potential contradiction of the origin given in the Chronicle.