I've tried them and I'm not a fan. Generally have a dislike of Rhoven unless he's doing something directly for the list's main trick. Carnage makes them Mat 10, which is damn near disgusting, but I feel they make a horrible target for stealth. You can generally get more out of Occultation on a larger unit or a jack. Hordes hates dealing with this guy because of negation, but Thyra has a hard counter to Hordes through silence of death. As far as Cleanse, I've never found a use for it. Getting rid of annoying animi is alright, but there really aren't that many defensive ones that menoth cares about. Arm 20 Carnivean? Whatever...hit for 11, I take 2. Menoth's sight is ok if you're shooting, but Thyra favors a highly melee-centric army. If you have 4 points left to blow, Rhoven might be alright for you, but he and his guards really have no synergy with Thyra.