1-2 Extra Chained Energised Hits and 2.5-10% Impact on Energised Hits.
Increased Cleave and 5-20% Heavy Melee Attack Damage on Energised Attacks.
Critical hit chance scales by your current heat level up to 27.5-50%. Also increases critical ranged attacks damage by 4-10%.
This is the veteran build I use to run the hardest missions in the game. Firstly, the Mk3 power sword works against everything, from slicing through hordes to slicing through the toughest armored caparace, it does it all. 1 charge, 3 light swipes, repeat.
The plasma gun is my favorite gun in the game. It is accurate, shoots through small walls, 1 shots most specials, and can shoot straight through a horde of carapace enemies as well as ogryn shields, which is unique in that nothing else can. Ammo is not much of a problem on high difficulties since Survivalist will regen the ammo with the sheer quantity of specialists you will be wasting.
I have built my plasma gun in a particular way, with maxed out damage (80%), +10% Specialist damage, +25% maniac damage, and with the longshot trait, you can 1-shot both flamer variants from with the first distance damage bonus. You can also 3 shot a mutie, but the main benefit is not having to shoot a flamer twice.
I don't use any keystones, instead opting to take various other bonuses that make a huge impact, such as significant toughness bonuses as well as elite damage increases. This allows you to more easily kill the enemies that are more likely to kill your team, and the toughness bonuses are huge when you can shout to restore all of it.
This build has many get-out-of-jail free cards for when things get heavy. Aside from the quickly regenerating ultimate, the frag grenades are great to toss at your feet when overwhelmed, or at a cluster of ranged enemies. When I use them I like to use them in bulk, and stack on the bleed effect. Also great for rager clusters and shotgunners, as well as bosses when needing to keep them stunned. These frag grenades will be constantly regenerating too with the 60 second recharge perk, as well the demonlition team trait that has a 5% chance to regen on specialist or elite kill. On auric, these are common enemies, so grenade count will be kept high. You won't ever be relying on grenade pickups.
So with this build you can handle just about everything the game can throw at you. Cleave through a horde, snipe the sniper, one-shot specialists, melt a line of ogryns, as well as regenerate ammo and grenades. Great for teams, great for solo when you need to come in clutch.