The sudden but inevitable betrayal!
[X] Kroak - The spirit of the firstborn slaan was rejuvenated by the Deliverance - not enough to personally act on the scale of the other senior slaan, but his true strength lies in his knowledge. He retains a wealth of knowledge of the lost might the lizardmen possessed once, and will be able to restore this knowledge now that he is capable of communication once more. He is still bound to his corpse, however, and thus he relies much on his Oracle Ten-zlati, who wields potent powers through his mystical connection to the ancient slaan, as well as acting as Kroak's eyes and ears when need be. If a way to revive dead slaan is ever found, it is no doubt Kroak will be the first brought back, for his resurgent might would be a great boon to the lizardmen indeed.
Looking back on it, someone who knows what the fuck all these artifacts are would be great, even if he doesn't know how to make them. All that good shit we got locked away becomes almost instantly available, with the best artifacts capable of doing crazy things. Might even be something to restore the dead slaan or up the spawning pool rates in there.
The fact that he's pretty much the Corpse-God Emperor of Lizardkind is also hilarious. While I really, really want Kroq-Gar rampaging through 40k and don't mind if Mazdamundi wins, I think Kroak would be a funner start for me.