Do you tank the Blood (and rest of the adds) on the boss ? Or away from the boss on Tich? We just killed Heroic Tich last night and tanked all the adds and boss at the door to the balcony on the left. (We are similarly geared as you guys - 885-890 ilevel)
Initially we were tanking them on opposite sides of the room like it is discussed in most strats. However, we are very melee heavy, so we just stacked them in one spot and our fire mages' DPS just sky rocketed with that. The Bloods dont have all that HP and you can nuke them down before they heal from his Vampiric Aura.
The stacked strat is very good for a fire mage. He picked meteor as T100 talent which is fine and will work much better with the stacked strat. I would recommend picking Cinderstorm and learning to use it. Also, stand in Dragon's Breath range. No Diadem
His legendaries suck specially for Tich where you font lust on pull.