I have come to a conclusion through close observation of a theory I had on why mob's can cast spells "randomly" targeting a person not currently on top of hate list. I have noticed that whoever has added the most hate most recently gets targeted, for example a pld tanking etc, and you have 2-3 melee fighting, if 1 of the melee were to WS and mob decides to cast a spell right after (PLD still has most hate overall on mob)then that melee would get targeted. Another instance was noticed when I cast flash to assist a nin while tanking, the mob will throw a spell my way immediately after. If what I just said makes sense, these are just a few examples that I have noticed, and I want to believe that this happens due to who has added the most hate to the stack most recently. If any others want to add anything and/or ideas to see if this is indeed what happenes, when we usually freaked out about why we just got hit with bio 3 and not the tank/kiter, it would be appreciated. I wouldnt have posted this unless I didn't think this was plausible.
XI Wiki

can only have 1 on and not both.
