Changed this up a bit, as I didn't have 3 dragons faster than Bloat.
Used a Twilight Clutch-Sister (1, 2, 2) instead of Spawn of Onyxia.
Started the fight with Wild Crimson Hatchling using Lift Off, followed up with Scorched Earth.
Swapped to the Clutch-Sister and used Twilight Meteorite, next turn the Clutch-Sister died.
Brought in Emmigosa and used Claw twice followed by by Surge of Power.
Bloat used it's cannon right after the Surge of Power, but at this point it had >200 hp left, making it easy to finish the fight with the Wild Crimson Hatchling.
consistently had him at ~50 Hp on the last strike before the cannon came back.
My 244 onxyian was too slow to get an action in before it died, i swaped to a phoenix hawk with speed enough to ninja in there and it died easily.
Had a few crit diseased bites cost me a bandage too. various bullpoop RNG got me right in a mess before i cleared this.
Was getting a lot of bad luck with my P/S Spawn of Onyxia with this, and it would always get one shot, so I changed it to an S/S Albino Chimaeraling (2-1-1), and it would perfectly with life-off to counter Antaen Cannon