If you're not familiar with BrM, the first post on this thread will give you all the info you could want about BrM. You should read it instead of asking us to basically quote it for you. I'd also recommend that you give this thread a read: http://www.mmo-champion.com/threads/...cs-of-survival.
A quick rundown of the answer you're looking for:
Blackout Kick requires 2 Chi and adds 6 seconds to your Shuffle buff. Shuffle increases your parry by 20% and your Stagger by 20%. Stagger is also increased by mastery. Basically, a percentage of the physical damage the BrM takes (which is the percent of the BrM's Stagger) is converted to a DoT on the BrM. At any time, the BrM can use Purifying Brew to remove that DoT, effectively negating any remaining damage on the DoT. Purifying Brew takes 1 Chi, so it can't be spammed for very long. Each time you use Blackout Kick, you gain an additional 6 seconds of Shuffle. The maximum time on Shuffle is above 5 minutes (That's as high as I've ever gotten it). Not sure if it's capped at all.
The first objective of every BrM is to keep up Shuffle at all times. Without Shuffle, a BrM is about as good as a WW at tanking.
Blackout Kick requires 2 Chi. To build Chi, you can use: Jab, Keg Smash, Expel Harm, and SCK/RJW on 3 or more adds. If your tank is speced for Chi Brew, that also gives Chi, but Ascension is generally better than Chi Brew for most fights. Expel Harm is of little use if you're not taking damage and with no vengeance. On Siegecrafter, SCK/RJW is of no use since it generates no chi while the mines aren't out. That leaves Keg Smash and Jab. For the opener as the offtank, you can start with Jab+Jab+BoK if your MT isn't able to hold threat. Keg Smash does a lot of damage and can easily pull threat with a crit. Just have your BrM open with a couple Jabs and BoK before he gets into his full rotation.
If he insists on using his full damage rotation off the start, you could consider letting him tank first. That fixes the whole issue without having him change up his starting rotation.
Not sure why this has been discussed as much as it has. Regardless of the specs of your tanks, if you're a tank pulling aggro off the other tank at an inopportune time, you have three options:
- Have the tank that you don't want tanking to reduce his threat.
- Have the tank you DO want tanking to increase his threat.
- A combination of the above two options.
Unless you're bumping up against the enrage timer, option one is by far the easiest option.