Halfus Heroic is a completly joke right now at 25s. Just free up 3 drakes (i'd recommend scion, stone and whelps) bomb whelps, free time warden shortly after (we waited roughly 30s for another md) and kill all drakes with cleave and multidotting. Druids, shadowpriests and affliction locks will really shine there. After that Halfus should be somewhere around 75%. Burn him without the hassle or any risk of tank death and proper cooldown management during roar and thanks to +400% damage you will finish him in just about one minute +-.
Right now he's only a dps check and nothing about stacking disc priests or perfect timing and well thought out tanking strategies any longer.