I sent the Sisters of Twilight (on top of Ceithin-Har) and the two Forest Dragons to pester the main army. In my case, I already had some high-tier units like Forest Dragons and Treemen. Split up your army accordingly so that the center and the flanks are covered. Given this knowledge, you could prepare your forces, especially your staunch line of spears. The flanking squads mostly have Skavenslaves, a Rat Ogre, and maybe a Packmaster. While the main army (with several Hell Pit Abominations, Mutant Rat Ogres, and Ghoritch) strikes towards the center, the squads at the flanks tend to be weaker. The thing is, Throt the Unclean and Clan Moulder will swarm you from multiple sides. You’ll also notice a timer ticking down denoting how long she has to survive. Now, the goal is to keep Ariel at the very center of the hilltop since this is where she can conduct her ritual.
The difference here is that Ariel and co.
The final battle still takes place in the Witchwood. I suggest doing these for the Witchwood and Oreon’s Camp. You can unlock The Root of Chaos final battle for the Sisters of Twilight after completing two Rituals of Rebirth.
