Despite theories about Ilberd, for the guy with a mask, it could be Widargelt, or...



...maybe Livia sas Junius.



Why Livia ? Because, if you remember well in the past Livia faced Yda and she was shocked because they had the same Monk skills (I guess) or maybe she recognized her.



Personnally, I think Yda and Livia had the same monk master back in Ala Mhigo several years ago.
So, because Yda want to stay to verify who is this Mask (could she suspect to be Livia ? ), and because Monks are related to Ala Mhigo, it's a possibility to not exclude.
And, it could be nice to have a motivation for Lucia to be involved in the story of the next expansion. She could met her sister Livia.
The good question is why Livia would do such a thing ? I think with Gaius dead, she has nothing anymore to do with the empire. So, what she want is to conquer Ala Mhigo, her beloved city where she was raised, and become the new queen