See
I have a problem with the concept of people who have access to Seers being ambushed and nearly wiped out to a man. This does not work, unless they let it happen for a reason. And yes, they can't see terribly far. But the closer it gets to the moment, the easier it becomes. Also, if they look far into the future and see 50 different futures, 40 of which involve them being ambushed. Or even if it' just 12. That's still a significant chance, and you take precautions.
also, if most of the members of the clan can slow time around them. Basically giving them superspeed/reaction. That is a formidable weapon in combat. If all the clans got together to do this premptive strike, perhaps, but really they should have seen it coming and done something. Unless they did see it coming, and saw that it was necessary for them to allow it, so that something more dangerous than the other Clans would think they were dead too. And being able to go back and see events that have already happened is hugely powerful.