There is a glitch that you can use that requires the dreadnought drop pod.
It’s quite hard to make, but it’s worth it once you’re OUT OF THE MAP.
What you need to do is go on the bottom left side of the map, wait for the door to open, go right near the ravine and spawn the dreadnought in the opposite direction, but in a way that allows you to be knocked back. When you are on the ground, click IN the ravine. Your Space marine will nicely walk in the air and join the right place. Then you go south, to the building wich can be garnisoned. You get behind it, then into it, and then again go out. It will make you higher.
Once all that is done, you can make easy kills while protecting your allies with the heal and revive ability. Because you’re out of the range of ennemies, they can’t shoot at you and kill you, but they’re still in yours (the range for the plasma cannon is awesome for that).
Note:if you die during the “god walk in the air”, you’ll just be brought back in the arena, and you’ll be able to be saved ;)

It also works with the Lord General (equiped with the sniper), but then again you need the dreadnought Drop pod.

It’s not easy to go out of the map, but it’s possible ;)
the Right of Swift victory is just there to help you tearing down for as long as you’re still in the arena ;)

I haven’t really used Oath, but I wouldn’t use it alongside grenades either for the same reasons, especially if you want to make use of Orbital Strike.

Switch out frags and oath of merciless rage for some purity seals like rite of fortitude and parable of stalwart brother.

heck, I’ve seen competent players decimate the Anvil of Khorne map with nothing but the clever use of bolter (+0.3 energy regen), an articificer armor build + orbital bombardment.

Plasma Gun: for Hellire grenade (aoe damage)

Artificer Armor: For ability spamming and decent survival.

Oath of Merciless Rage: for merciless strike (aoe damage)
Frag Grenades: (aoe damage)
Jump pack: for escape.

Orbital Targeting Beacon: (MASSIVE aoe damage)

Not sure if that is an optimal build but is sounds fun to me. If anyone is willing to try it and tell me the results that would be much appreciated. Otherwise i’ll just try it for my self when I get the time. ;)

Power axe.

Combat shield (if not cause that is dlc) use plasma pistol.

Armour of vengance or Armour of Fortitude (for 2.5 regen).

Jump Pack.

Parable of the stallwart brother.

and the revive (red one)that lets u revive other players and gives em imortality for 10 secs.

Laramans Blessing. (Eagle11 was on the right track) :)

High attack rate paired with zealous leadership keeps you up in addition to massive +5 hp regen and wih captain’s best armor. The lightning dot applied from claw helps with everything but be careful to not tank multiple heavies at once or melee swarms.
Everything is even better if you have an Ork with Boss pole behind you that doubles your health.

Chainsword + Bolt pistol (Use Plasma for more damage and less tankyness)

Armor of Vengeance

Rite of Fortitude
Litanies of Zeal
Jump Pack (Your way of escaping once damage is overwhelming)

Larraman’s Blessing

Switch Larraman’s blessing for Dreadnought and Sword/Pistol for Thunderhammer for some meele funtime, especially versus the Wraitlords on wave 12.
I lol’d loudly when I chainstunned them.