Okay there has been some discussion on the process of dealing out whirlwind.

Using an action you can perform an attack with a melee weapon targettng all adjacent monsters. "You mkae one attack roll and each monster rolls its defense dice seperately."

So it should essentially be the single attack the targetted mob and the same total damge is then applied to any mobs adjacent. The Warrior is using the Iron battle axe which aotu applies +1 pierce and has surge options of +2 damage and +1 peirce. The warrior rolls the dice and gets two surges. So the initial takes the damage plus the 2 extra damage and the +2 pierce. The whole attack should also be applied to the adjacent mobs via whirlwind which means the +2 damage and +2 pierce should also count correct?

that is 100% correct ( to lighten the understanding, the attack is first made when the hero desides what to use the surges on)

Yes- the attacker rolls once, and all the defending figures roll separately. After dice have been rolled, if the attack hits, it's time to spend surges, like a normal attack. Whatever the berserker chooses to be the final attack result (you rolled 4, but spend a surge on +2 and a surge on pierce 2) is what all of the defenders are defending against. All multi attacks in descent work the same way in terms of rolls. The timing might be different, as in something like blast, you might spend surges before some defenders roll.