Normally its a caster that has to do this job, and I had to do this job on my Wizard, which was not easy. Firstly they do far too much damage to be tanked, they are immune to Power Word Kill (tested), they are immune to Power Word Stun (tested), and they are immune to Otto's Irresistible Dance (tested).
Honestly the only ways I see possible are either kill them with Niac's Biting Cold and Ice Storm or kite them. Both strategies aren't great as you don't really have that much kiting distance due to Velah's fire attack, plus the fact that she can knock you down even if you are behind a rock. Also, my wizard doesn't have the SP necessary to kill every Reaver/Render out there with cold spells, at least not without using pots.
So my question is what do you do about the trash mobs in EVON 6?