Fortunata Widow, using the melee attacks, time of about 7m 40s.
T2 Musc, T1 Degenerative, no other incarnates, just a cheap (almost) perma hasten build with 1 proc in each attack. Rotation was Aim+Shatter Armor and then Followup-Lunge-Strike-Swipe, reapplying shatter armor haphazardly or after each aim usually meaning I did lose some uptime with it, though I did try to use it after Followup-Lunge so as to maximize the usage of the better attacks. Lost additional time to having to aid self like 4 or 5 times due to eating a hit and messing about with hasten/mind link AND I had to use a blue insp to stay afloat even with tough turned off.
I'm honestly not sure if I'm happy or sad about the performance lol it was the first pylon I've ever attacked. I feel pretty powerful in general play so I was actually fairly surprised it was as slow as it was. I'll definitely be interested to see how it goes with more incarnates. I'd also like to try Night Widow, I've heard Slash isn't actually that great of a DPS gain but it certainly FEELS like less not having it lol
Edit: I forgot to mention I had the supergroup base +recovery and +Recharge buffs as I basically always do the whole time I play any character.
Second Edit:
Did another run, this time with my Illusion/Traps Controller, 205% Global Recharge, Ice pool, level 49 so no incarnates yet, Time was 4m 13s.
Ran a priority list for power usage, I kept the army up of course and then built acid mortars first, applied poison trap for -regen second, resummoned phantasm third, got decent uptime on him by keeping him flanking the pylon, and lastly filled with a damage rotation consisting of Ice Storm>Spectral Wounds>Ice Blast>Blind.
I got hit by the pylon and knocked two or three times but it was a pretty clean kill besides that. I'm honestly shocked the gap was that big compared with my Widow, especially since I'm not even 50, though I did expect this character to do fairly well considering AV slaying is like her life's calling.