• The party first encountered the Assassins Guild in Episode 11. A hit was placed on the Solarum of Solas. 

• In Episode 12, the party discovered the guild hall in Solas' Cemetary and killed those present-- namely, Vexalia and Vaxeldan (twin assassins and leaders of this branch of the guild). Vaxeldan was taken alive to Lady Katherine's estate where she "took care of him". 

More about the nature of the Assassins Guild may be discovered.