This boss can become very simple with the right teammate.
Our DUO strategy was I kill the trash mobs and he focuses the boss.
My stats were around 90 Armor (25 weight) a shotgun+5 (summon mod) and the default pistol+5 (hunters mod)
His stats were about the same but he was running a sniper+5 instead of the shotgun.
The boss has a few attacks flamethrower, fireball and a charge up one that summons fire below you
flamethrower try to stand away from him behind cover if possible.
fireball with light weight (-26) the fast roll is enough to dodge this but pillars and the trash mobs can all block this ball.
final attack this attack is a little more complicated he doesn’t start till more than half dead he will stand up on his back legs and stretch out his wings when fire appears on the tips is when to dodge. Once you figure out the Difference a simple run or dodge will be enough for this attack.
final notes learning the attacks and trash control is priority.
solo focus on killing the trash as fast as possible.
duo one person on the boss while the other takes out the trash mobs.
trio I would have 2 on the boss but it may be better to have 2 on trash.
my first actual guide, can definitely be improved. Thanks