This is why I was unsure and was asking BB durability questions at the beginning.
My one real memory of his durability was in War of Kings when Gladiator hit him hard enough that the gigantic glacier they were standing on was mostly shattered by the impact and he was up and around looking pissed within 30 seconds or so rather than being hurt. If him being able to eat hits from Gladiator was consistent then he'd be beyond Mark's capacity to hurt.
As it seems he's not, Mark can just blitz him and tear his throat out like he did to Thragg.