Don't switch on Spikes by casting a Fireball only switch with your Pyro. Except if you saw on last spikes that the raid doesn't properly handle them, in this case switch with your complete rotation (except the Living Bomb)
Right before the Bone Storm try to be at max melee range (without standing in coldflame), and when the storm starts and if the boss stays on his location use a gcd to be at a range you will take reasonable damage
If you have issues to handle flame damage during the storm, use your Frost ward before to prevent an unfortunate death. But remember it costs you the 1.2 sec of GCD to do it.
Nothing special in heroic. But make sure you are helping on spikes during the storm because you have one of the longest range in the raid !
Switch on spikes with your Missiles, you will burst them faster than anyone and your mates will not have to move for the spike you have shut down. If the Spike is already harmed switch with Arcane Blast, because this spell has no travel time, which will ensure you do do not lose any of your damage.
If you have Incanter Absorption you can get a very nice SP buff on this boss. By absorbing some tics of coldflames.
Nothing special in heroic.