Pre-50 just use flash and cycle rage of halone combo on groups.

After 50 you can flash + Circle of Scorn then use Total eclipse on groups (and flash some more to keep them blinded and the enmity high). Also good to pop a cooldown (rampart, sentinel or bulwark) to help your healer if you have a large group.

After 50, rage of halone really is only used on bosses.