Expedition mobs

Yesterday I did an expedition on a T5 map which should be easy for my character, and of the mobs that spawned in, I was able to kill the rares, but the magic monsters that supported them were basically unkillable to me.

The thing that made them unkillable was that they had a MASSIVE energy shield that would take me minutes to get through and the moment they would run away it will fill up again in a second, and they were all ranged units so they were always kiting me (they were scorpions and skeleton mages) especially the big scorpions as they moved quick.

I was able to beat everything else in the map except them as I eventually just gave up. The map modifier did have a roll like "enemies 29% of their health as extra energy shield" or something like that so that was certainly a factor but as I said the rest of the map was easily doable for me, so likely these expeditions monsters had a big innate shield and it scaled hugely.

The runic monsters seem to have hidden mods, or at least I don't know what the little icons mean on them. Anyways I guess my questions is since I'm using a melee physical damage bleed build, what are some strategies to deal with big energy shields? Cause it seems like I couldn't leach properly from them either as my mana was running out, but when I use lifetap then I could sustain, but the main problem was that the shield was a huge value and it would restore the instant they moved away from me.