Not saying this to sound pompous but he really isn't anywhere near as tough as he seems.
He will become extremely predictable if you study him for a bit. Just bring adamant seeds to remedy his drool def down status and nulberries to remedy his dragonblight.
If you're bringing traps, don't use them until he's hungry.
I think its the music that kicks in that does it.
Would love to fight him one-on-one to learn him but he always appearing in something else.
I never know what to do when he does that multiple lunge/sweep thing. Always batters me .