On one attempt last night we got Brutallus to 2% when he enraged. The kicker was we reached that point with zero deaths and only 7 healers. For this fight we have a paladin and druid on the burn victims, 2 shaman covering the raid, and 2 priests plus me on the tanks. My job is to max my +healing and spam Flashes from beginning to end. I'm talking spam where I do nothing but watch the global cool down and cast as fast as humanly possible. I listen on vent and only switch tank targets when they call out a taunt. I'm not even watching my target.
In a way it was kind of fun, like a mini-game against myself. How close could I cut trying for the next cast and how fast could I recover from a flubbed one became the goal. I was also interested in seeing what kind of numbers a pure Flash fight would give me.
On the best attempt, I cast 155 Flashes for a total of 540,414 healing and 27.9k mana used. Based on a 6min 24 sec fight, I have just over 1.4k HPS. That's pretty close to my predicted 1.36k HPS from last week. My exalted MH ring procced 6 times for a 3.87% chance. My average cast was 2.1k hp with my max at 2.2k. The part that makes me wonder a little bit is my albatross only returned 750 mana instead of 900. It ticked 10 times for 75 mana each. I missed 2 ticks. Looking at WoWHead, the trinket is bugged and only ticking 10 times. The Owl version is in the same boat. Hopefully it gets fixed soon. That missing 150 mana is almost 1 Flash.
Currently I have a calculated 1.45sec Flash cast, since I wear my mana regen cloak for this fight. I start the fight by clobbering Brutallus with a JoWis and running back to my spot. I also have to proc my shield for burns and my mana regen macro at least once. Luckily WWS lets me pull up my log. Grabbing the first page of info (~50 data points), my average cast time on Flash is 1.6 sec. The minimum is 1.2 sec, probably due to Bloodlust. That's with around a 200-300ms lag and 18 fps. Not bad imo.