Story boss? Or anything that isn’t a moving around monster? Asking mostly for the graft perk.
iirc, it is every battle that is not the normal monsters walking around visibly. Could perhaps also include some of the battles from certain things like the blood on the ground.
I am pretty sure that getting attacked when you touch an object in a realm doesn’t count for Strife, but I would need to load up my Death Mage game to verify and I don’t have my laptop with me at the moment.