Battlelord Kreshan is pretty easy if you stay away from his bombs and his Sweeping Gunfire. You can run away from both attacks without much difficulty, but Sweeping Gunfire can also be interrupted IIRC (it's been awhile).
In my experience, wiping on Kreshan usually happens because group members ignore positioning and just take Sweeping Gunfire or a bomb straight in the face, assuming they can shrug it off like an attack from some random mob.
Exactly. At the beginning, the tank should take him and face him towards the console behind him, and the rest of the room is to DPS and healer to avoid aoe and kill adds in. The sweeping blasters will also not change direction after it starts casting, so even the tank can sidestep it.
If everyone avoid the aoe and the dps kill the adds as soon as they spawn, it's a very easy fight. As a level 15 healer I've healed dps trough it after the tank got himself killed, and then healed handled it completely solo at 17 when the rest of my group did the same (by getting knocked into the pit and standing in the aoe). An operative won't be able to handle it solo that way (I could only do it by using my knockback to throw the adds over the edge when they spawned), but sorcs and mercs should.