Slythernak

The Slythernak are a Titanspawn species that resemble a demonic, humanoid, rat-like creature. Created by Akarosh as his master race, they are a highly mutable species that can adapt castes for very specific roles. To augment this capability, the powerful spellcasting caste has researched fleshwarping capabilities. As a titanspawn race they have a deep hatered of races not created by the titans and see the total annihilation of non-titanspawn races as a divine mandate, especially as the mortal races gods were responsible for the death of their creator

During the Titanwars, Akarosh unleashed numberless hordes of his Slythernak against the other Titans' creations. The effectiveness of the Slythernak necessitated unexpected alliances to kill Akarosh and destroy his armies. This was initially thought to have been entirely successful, with Akarosh cast down, his blood drenching the land he'd stood upon, and the Slythernak killed to the last one. 

However, it was later discovered that a number of the Slythernak had escaped into the Darklands, where they had been rebuilding their strength.