Tanking issues

Hello guys,
I do have a question about keeping aggro on bosses. I'm playing KFM but it seems this is also applicable to BM. The first issue is that KFM seems to have no threat on skills in this version, I've been told that BMs have the threat spec on block skill however no one uses it because there are better skills to slot in accessories.

There is a pill which boosts threat for 30sec however the cooldown is quite long since usually in the 5minutes of cooldown time you are already on 2nd boss. Also in my case the pill does not work since for some reason FMs are able to take over the aggro.

Do you guys have any tips how to tank and keep aggro on boss, since it's kinda annoying when the boss is running all over the stage and changing aggro like crazy.