Alright so seeing as tactics are preferred to be up in this section, here goes.
Two links here, they both have the same general theory of boss-kill.
http://marks-365.morynne.com/2011/05/st ... rmbreaker/
http://www.stratfu.com/strats/halfus-wy ... breaker-25
Extra info taken from these -
Each time a drake dies Halfus receives a stack of a debuff which increases the damage he takes by 100%.
More importantly for your healers, it also drastically reduces the incoming damage.
The quicker the raid can kill a dragon the greater your chance of downing the boss.
For this reason all DPS with the exception of the interrupter on Halfus should single target burn down drakes.
The only target suggested against killing first are the whelps. The whelps can easily be dispatched through splash damage from AoE.
The raid should ignore DPS on Halfus.It is important that the raid does NOT push Halfus below 50%
until all three drakes and the whelps have been killed.
If your raid got to this part the only issue is to beat Halfus's 6-Minute enrage timer.
With the 400% increased damage taken debuff it shouldn't be an issue for most geared raids.
Heroism is best used in the first 10 seconds of the encounter. As soon as the drake that you can DPS is active and the tank has threat
you should pop the buff. This helps with healing on the most difficult portion of the fight and pushes the raid out of the phase (the most damage intensive).
It is always a bad idea to save Heroism for sub-50% because you lose a lot of DPS/Healing uptime due to the Furious Roar.
Don't release all 5 drakes, leave the Slate Dragon chained the whole fight. The debuff is not worth the time to burn through the hit points the drake has.
Make sure there are no drakes alive when Halfus gets to sub-50%. The drake will continue to attack (and probably kill) the tank.