https://www.grimtools.com/calc/q2MrOo7V
This is no work of art but it plows through campaign. As you can see i might need more gear and im unsure about the skills. I found that medal and gloves thats why i tried mortar. But i cant do a SR65 in time…
Maybe i shouldnt even go with the mortar?
Gear: Korvaak relic is better.
Skills: The Big One is useless. Get Deadly Aim to 12, Vigor to 3, max Flame Touched and Ulzuin Chosen. BwC to 12. Take those 3 points from Temper. If you’re using Flashbang, get it to 12.
Components:
Head = Prismatic Diamond (almost) always
Chest and shoulders = 95% time either Living Armor or Sacred Plating.
Amulet = Seal of Annihilation (almost) always. With spell cost redux it gives you better energy management than Ectoplasm.
Rings = Bloodied Crystals always
Weapon = Seal of Destruction. You need the granted active skill Stormfire.
Others = never Antivenom Salve always Ugdenbog Leather
Devotions:
Start with Torch and go backwards. Take Kraken, Witchfire, Bat, Ghoul for sure. Hydra, Magi, Hawk are good to see if you can fit them in. Crown is not a 100% must since you got BwC. See if you can take Candle and Lotus for energy.
RR from agonizing flames and elemental storm does not stack. Do not spam BWC, get the transmuter. This should save you some energy.
You also need better components, and your belt did not even had an augment.
Skip “the big one” and get flame touched and ulzuins chosen to max.
Get Word of renewal modifier.
Mortar trap or not… it require monster to stand still so it can be hit by it. BWC is more kite-friendly.
Korvak relic is better
Shit I missed that. 
And that
Two eyes are better than one

Phew… Farming time inc. Alcohol and coffee is needed 
But if not Mortar. What could it be replaced with?
Mythical Pyroclisms Mark, Mythical Hellborne
https://www.grimtools.com/calc/qNY8j37Z
Here is my build. It rocks thru the game… DPS hits almost 180,000
you dont even have maxed resistances, or not even thermite mine. + OA is very low.
Your retaliation damage is pretty low, so it wont add that much to bursting rounds.
with some small changes you would see immense improvment.
https://www.grimtools.com/calc/YNn0wzgV
changed skills to include flashbang for DA shred, thermite mines for RR.
Changed relic, changed component in gloves and medal.
Still low OA and resistances overcap but should be better now.
Thanks for the input but have to disagree a bit. Changing relic loses too much and little other gain. Same with the other changes. Not used flash bang before so will try that out. Much appreciate the look
Well its your char, I would never play with such low resistances and resistance reduction 