Boss Battle: Queen Thyra
Queen Thyra looks like a giant multi-eyed ice bug with huge, nasty blades on the end of her many “arms.” She holds Yeros captive.
As with all bosses, as long as you keep moving you should be able to avoid Queen Thyra’s attacks. Unlike Corallis and Old Mawood, you aren’t strictly restricted as to which Elemental Warriors you can use to get the job done. Chilla and 40 Below are generally the best warriors for the job. 
Use 40 Below and continuously circle the battle platform (careful not to plummet off the edge), avoiding Queen Thyra’s attacks (a bluish-green flash precedes her strikes, telling you where she will hit). Eventually, she will pause long enough for you to change to Chilla and fire an Ice Spike into one of her green eyes (any eye will do, but it must be open when you hit it).
After you strike the eye, it will burst forth and turn into a multitude of bouncing green eyes that must be knocked off the platform to destroy them. Change to 40 Below, create a Snowball (LT+RT), then use the Wrecker Ball (RT) power to rapidly knock all the eyes off the ledge. Repeat this process until all of Queen Thyra’s smaller eyes are destroyed. If you need to keep your health up, assign the Eye of Restoration (if you’ve acquired it), or switch to Ash and use his Incinerator power to regain some health.
Eventually, you will be faced with Queen Thyra’s final eye, which is very large and attacks you by growing spikes and bouncing after you. Keep moving until the eye becomes tired, at which point the spikes retract and it ceases its attack. Use 40 Below’s Wrecker ability to knock the eye off the edge of the battle platform and defeat Queen Thrya.
Yeros is now freed and fills you in on some more history about Kameo. He also rewards you with Snare.