I looked at your stats and I still don't understand how a mortar is only hitting for 500-1.2k damage even with the leap. Either way props to you sir for beasting it up.
Thank you, I try and avoid the mortar fire as much as possible. Breaking line of sight causes them to approach you and it also bottle necks them so that you can minimize the surface area in which they can attack you.
If I am standing at a corner for example, I force the enemy mob to come within melee range of me where he cannot hit me with mortar fire. I increase my armor with leap and now he must fight me where I am at my strongest. Further, his allies won't be able to hit me with mortar fire either until they funnel through the choke, and even then they will only be able to attack me with melee attacks. The damage from which is dramatically reduced through the armor buff of my leap and which also procs revenge. Good for me, bad for them.
Last thing about those mortar mobs, the AI for the mortar mobs that I fought is not very good. Towards the end of that section of video you can see me abusing the AI a bit. I stand too close to him to be hit by mortar fire, but out of range for his melee. So the mob stands there staring at me, then eventually decides to cast his AoE lightning. Which by the way, I feel is the weakest ability out of rare mobs in the entire game. It doesn't do much damage and he stands there letting you attack him. If you wanted easy farming, I feel like those would be the mobs to target.