Bridge Over Troubled Fire

If you are clearing up your missing achievements, like me, make sure you check the dungeon is set to Heroic. If you are level 110, it defaults to mythic, therefore, you will not get the achievement. Wasted time trying this, only to realise too late.

When boss flies the first time, do not kill the adds. Kite them and cc them. After the 2nd time the boss flies up, another wave will appear.

After all drakes of the 2nd wave spawn, gather them all and AoE them down. Try to not push the boss to final phase (he lands on the bridge) before 2nd wave, but that is highly unlikely as of now dps-wise.

Mage 110 ilevel 906 just a tip:

DPS Boss Lightly till 60% ; wave one, KILL NOTHING.
DPS Boss Lightly till 30% ; wave two, wait till they are all together, then AOE the adds.
I popped Frozen Orb, Cone of Cold and a few ice lance and achieve popped instantly.

PRO TIP: If you dps too far down too fast he wont send another wave of adds... or even one. You might just over power it.