How to stay invincible in mobs?

I want to know how to get the most out of invincibility in mobs. Basically, how do i pin multiple bosses in a corner while minimizing the vulnerable periods? I was thinking bsb on top of them, csb back without pushing them (i don't know if they won't be moved), barrage and repeat. If somone could test if the CSB wouldn't push in that situation i'd be grateful.

Also barrage jump back csb won't work very well because the other boss might break free.

Takebacker asking for help about control?!?!?!?!?

*checks thermometer* No, hell hasn't frozen over...

*leans head out window* No, I don't hear an obese woman singing, even though I do live in america... *cough*

*stares into the sky* No, pigs aren't flying.

WHAT HAS THE WORLD COME TO!??!?!?