Yes, you're on the right track. Once you get to Brayflox, then things start to toughen up a bit and you start seeing your HP plummet down more. Focus your Rage of Halone combo on the target of your strongest DPS.

Shield lob is always a good opener. DPS will also automatically locked into that lobbed target and can start their DPS as soon as possible.

Flight or Fight whenever it's up, and Rampart when you're taking on a lot of mobs. Sentinel when a big hit is coming. Bulwark and Awareness in big pulls. Convalesence when you expect things to go down.

Also, for your information, Rampart and Sentinel stacks up multiplicatively. Means if you use Rampart + Sentinel, the damage will first go through Rampart, the resulting damage will go through Sentinel, resulting in around 52% damage reduction instead of the additively stack, 60% reduction. So, it's better to use your buffs back to back, instead of stacking them all up at the same time.