I'm really curious about the physicality of Niddhog at this point. The majority of his actions in 3.2 seem to imply that the dragon form is just an aetherial projection and can't do anything physical (hence him swapping forms at all - Estinien's body is the only physical aspect that Niddhog currently has, so he needs to use it to attack Vidofnir/can't use his dragon body to attack the assembled Ishgardians). But then, he can also fly, which Estinien decidedly cannot do, so I dunno.