But essentially the buff for ICC and DS were just implemented so that people with less gear can kill the bosses.
The boss has already been solo'd. Basically taking on this challenge as "world first solo LK without the buff" is essentially just killing a boss that has already been solo'd, just with more gear. It would be a cool thing if you enjoy soloing stuff, but not really newsworthy imo. Might consider finding something that hasn't been done before to solo.
easily doable I think, with current gear and 4.3 vengeance change I kill normal LK in around 8-9 minutes without especially pushing my DPS, and probably wouldn't have much trouble doing it at all without the buff. I actually have to wait down a little on normal mode because of Necrotic Plague not killing ghouls quickly enough, and still having multiple vrykuls up during the first transition.. -_-;
to be honest, LK without the buff can be summed up as nothing more than H LK, which is basically the exact same as normal LK with more hp and damage. The only thing that prevents soloing H LK atm is the frostmourne room which means a tighter enrage, and my best attempt on H LK is at 15.X% aka so little difference from a kill. remove the frostmourne room (normal mode) and it becomes easy as pie~