The eternal's turn isn't exactly "fixed", she just has 46 initiative on tactician if I remember correctly, I was able to act before her on my lone wolf mage, for none lone wolf chars it might also be possible with a lot of initiative gear and clear mind spell, and then maybe you can do a blessed smoke cover to invis your entire team.
There are enemies with up to 56 initiative on reaper's coast but almost all of them follow the rules, the only exception I found is the wolf abomination who ignores initiative and always gets a free turn, which is probably a bug.
