Macros my friend

SHIELD SLAM

/cast shield slam
/cast shield charge
/cast shield charge
/cast berserker rage
/cast heroic strike
/use 13
/use 14


REVENGE

/cast revenge
/cast shield charge
/cast shield charge
/cast heroic strike
/use 13
/use 14


DEVASTATE

/cast devastate
/cast shield charge
/cast shield charge
/cast spell reflect
/cast mass spell reflection
/cast bloodbath
/cast berserker rage
/cast heroic strike
/cast gladiator stance
/use 13
/use 14
/cast demoralizing shout


Put them in this order on your bars

Devastate, Shield Slam, Revenge


Pop Bloodbath, shield slam, devastate, revenge, devastate, (if shield slam procs, use it in a higher priority to revenge).


Basically weave every single attack into a devastate.