Catrhis: It does, certain conversation require 2 or even 3 in delusion to work, plus the delusion ability must always be equipped in the skills slot to work even in dialogues, i personally think that that's stupid but until modding fix that , so it is
Delusion is also pretty useful in combat as the Axii sign is too slow to be used otherwise, plus it add a nice stun effect to the target when used, a powerful combination if used with the Rend special attack and enough sign intensity
Actually i think that with it's stun you don't need Aaard at all in combat as you can go for Axii instead.1vs1 it makes you a boss and even if you faced couple of enemies you can stun one of them and kill him fast or deal with the others when he is stunned so literally you have -1 enemy for this combat situation.
