Besides Nunu now looking AMAZING, his bio now has some very interesting stuff regarding Freljord's story.
Here's a little tl;dr before i get into more detail:
1. Freljord is cold and snowy because of Anivia
2. The Frostguard are kind of the good guys on the surface and none of the people know Lissandra's an evil Ice Witch (Yep, still their chief)
3. Lissandra wants the power the last Yeti (Willump) has. Possibly a world rune!
4. The Yetis took part in burying the Watchers (presumably) and Willump met the three sisters
5. There's dark ice in the heart of the Freljord with the Watchers in it, and it's melting
So, we already knew Anivia was one of Ornn's siblings and this story lets us know that just like Ornn and Volibear, she shaped the world around her. There's still not much on her yet, but this is a nice little nod to her influence as a god-like being.
As for the Frostguard, I'm really into their story. From Nunu we learn that they are considered powerful and noble warriors. Back when Lissandra was first released we also learned that they are considered peaceful, guarding the North and it's secrets. However, they serve their leader Lissandra above all else. And as we know from her story, she is actually the Ice Witch of legend, disguised as a noble leader. She waits for the right time to strike with her Frostguard as she lets Ashe and Sejuani fight to the death. It's amazing that Lissandra managed to keep her cover for so long, as she's been erasing all records of herself throughout history. We can see here that she's very busy trying to find as much as she can to aid her cause.
Now, Willump recalled the three sisters as well as the ''betrayal by the blind one'', which means that he must be aware of Lissandra's affiliation with the Watchers, as they are presumably responsible for the Yetis loosing their magic. This magic might be linked to the Watchers sealing, which may explain why Lissandra wants to find their power so bad. Guess we'll have to see.
FINALLY, the Watchers are thawing. Their return has been announced since Lissandra's release, but substantial has happened. This proves that they are indeed thawing, meaning that when Lissandra sealed them back in Ornn's story, she purposely left a loophole for them to return. Can't wait to see how they are connected with the rest of the lore and how the people of Runeterra will react to their arrival.
Please speculate away, as you can see I'm very hyped and do let me know if i missed something important!