Make sure to use Glyph of Devastate & Glyph of Sunder Armor. I usually never have low rage in heroics atm so I usually Charge, Thunder Clap, Shockwave, toss two Devastates on the first kill target and one or two Devastates on the other mobs.

I can usually just spam Heroic Strike while throwing around devastates on the mobs and use Shield Slam when its up. Usually I dont shield slam until I've established aggro on everything with a few sunders unless Sword & Board procs.