I kept trying LR-5 Sentinel for somewhat 3 hours. We had quite a good group, but on HM it's impossible.
I got full Columi with 4 Rakata items.
The setting we had was:
SI Assassin (tank)
SI Assassin (DPS)
SI Sorcerror (DPS)
BH Mercenary (Healer, which was me)
I can easily keep them alive, that's not the problem. We even figured out the tactics ourselves, but at 26% we keep dying. For some reason he gets a buff which tells us that he "Lost control over the machines". So the Lighting Bolts on the floor are being placed as big ones without a warning. The Lava from the floor goes on all Platforms. So pretty much, we aren't save on any spot.
We kited him very well, and I can Cure the tank as soon as he got a Incinerate DOT.
-The way we were kiting was as following:
The ranged stand on the middle platform, while the tank brings the boss to one of the side platforms (where the adds come from). When we get a Lighting Charge on our spot, we move to them, but we stay behind the boss. After a second Lightning Charge he moves the boss to the top or bottom platform. Again we repeat the same thing, when there are 2 charges, we move to the next platform. And when the middle one is free, the ranged stand on that one.
But when on 30% or so, we cant stand anywhere.
I'd give a vote to Downtune him a bit. Makes the damage from the Lava less, or the Lightning Charges not so big. I don't know.
The FP is not over tuned, difficult yes but not over tuned. One of the first things me and my friends did in 1.2 was run the FP on hardmode.
Scoundrel Healer (Me)
We died many times getting the mechanics down but it is certainly doable. I'm glad HARDmodes are finally hard.