Ivar the Boner
Arcane
The only way I could deal with the mutants at iron forest was with the the dragonov sniper rifle from the southern plateau and to approach the area from the eastern side near the electrical anomalies. From there it was a matter of leaning around the wall and massive amounts of luck, timing, quicksaving and save scumming all the while popping off shots before the controllers one shotted me. The PSEUDOGIANT just eats ammo so I threw nades and pumped him with rounds from any and everything I could. AP rounds work best. The poltergeist was the easiest to deal with overall since for me it stayed near the downed Hind and patrolled in a pattern with let me snipe it before the annoying dance with the controllers even started.
Poltergeist is main problem for me, I managed to deal with one controller easily, savescummed my way through second one and then just avoided Pseudogiant. Unfortunately I'm terrible shot and I have problem hitting humans with my SVU so I can't snipe semi-invisible poltergeist that screws up my vision with his psy "field".
So I just grabbed tools and retreated hoping that controllers won't respawn and I will be able to deal with poltergeist later. Or maybe wait for 2.0.3 patch and start new game as Recon because I'm absolutely no good at sniping.