I just thought of a way to potentially bypass the philotic threads. What if Fenris just manipulated the lower dimension it wanted to manifest in and created an avatar within it but in such a way as to make it seem as though he/she was "teleporting" or instantaneously appearing in different locations throughout existence? That way the avatar itself would not suffer any ill effects as it's being created in the dimension and thus doesn't have to go through the process that Tier Four's do when dimension hopping.