[I was looking up what banishment does and I think that should've been a CHA save, but my mod for that is even higher, so it doesn't matter. It's a success in any case, just wanted to point it out

]
Hearing that sound is audible again and resisting your banishment's effect, he says through a guffaw,
"HAH! I'm glad you abandoned your silencing trickery. Now I can ask you if you have any last words?"Gul'Ragg gleefully starts swinging his axe again, enjoying that his battle roars are audible again.
[Action 2 attacks, packed with some smites if they hit.]
Greataxe to hit 1d20+9 : 19 + 9, total 28
Slashing damage 1d12+4 : 9 + 4, total 13
Radiant damage 1d8 : 3, total 3
Greataxe to hit 1d20+9 : 7 + 9, total 16
Slashing damage 1d12+4 : 1 + 4, total 5
Radiant damage 1d8 : 6, total 6
4th level smite 5d8 : 7, 8, 5, 3, 5, total 28
3rd level smite 4d8 : 7, 7, 2, 4, total 20