The CS phase is somewhat complicated due to Bloodsurge but I will attempt to break it down as easily as possible;
- Use Bloodthirst until Enrage procs
- Use Colossus Smash once Enraged and preferably with 60-90 rage. Too much more and you can cap out easily, too much less and you can rage starve. Better to go in with more than less.
After CS hits you will have three 4.5 seconds left on Enrage, or 3 full GCDs.
1) First use 3x WS first to spend rage and keep from capping
2) Use Storm Bolt if talented
3) Use Raging Blow
You will now have 1.5s / 1 GCD left on CS without Enrage. Despite it being our lowest damage attack, the best thing to do is use Bloodthirst to get Enrage back up again, you simply shouldn't have much rage left over for anything else.