Following a thread from the discord beta-testing channel with the proposed Sweeping Strikes as a passive buff to whirlwind / general aoe damage ability / damage over time.
Going down this route seems like a missed opportunity to add a tool to martial characters that would actually benefit them and their role in group dynamics.
If we think more along the lines of Quakeshock and the utility that provides it will get us closer to something more dynamic and interesting to play with in group settings. It has the overall effect of temporarily slowing melee damage intake to allies who pull too much aggro. Whirlwind has a similar effect.
I think Brumm's first assertion was to negate regeneration on bosses like Belphegor with substantial damage over time. While I agree the added guaranteed damage over time would help overall I don't think it would help against bosses who can merely teleport away and jaunt. That's a well the bosses continue to draw from (Vrac) leaving melee always a step behind.
The addition of Dark Mages and the development of the massive AoE spells has made it abundantly clear that burst damage, mobility and surprise are the tools we currently have at hand to mitigate inevitable death. 2k+ health / 2800 epic Warding go a long way as well.
A melee based damage over time nor a passive increase to an 18 second cooldown ability would help fight dark mages or Belphegor. The proposal for conceal reduction as an avenue for Burst Damage got shut down understandably. So I'd like to propose a disruptive option in the vein of Quakeshock and Whirlwind for fighting mages specifically.
Type of Feat: Combat (Fighter Bonus feat)
Prerequisite: Improved Unarmed Strike, Monkey Grip, Combat Expertise, Base Attack of +25.
Saving Throw : Fortitude
Cooldown Time : 30 Seconds
Specifics: With an unexpected backhanded blow the target is temporarily stunned.
Target must make a successful Fortitude Save against a DC equal to 18 + (Strength Modifier + Dexterity Modifier + Intelligence Modifier + Wisdom Modifier + True BAB)/3 or suffer 1d8 points of physical damage per True BAB and be stunned for 1 round.
The formula was targeted at 50 DC for a 20/20/10/6 Ability modifier spread and Full BAB this leaves Belphegor a 50% chance to save against this effect. I recognize this would be moot if Belphegor is simply immune to stun which I suspect is the case with limited Quakeshock tests. The long cooldown and short duration gives melee incentive to time their strikes well and gives them a proactive tool to help the group mitigate impending AOE damage from mages.