Please tell me, whats the best way of killing the Obliterator?
I don’t even know what to advise, I have a couple of ideas.
The OBLITERATOR has armor (damage absorption) worth 100, that is, you need a weapon that exceeds damage above 100 with such damage there is only one weapon Heavy Rail Gun 120 armor-piercing damage, only this weapon can cause at least some damage, but I’m not sure, because the OBLITERATOR's armor absorbs armor-piercing damage by 20%, that is, the strongest weapon will only do 88 80% damage and therefore will not penetrate the armor and will not cause damage.
I'm not sure of my calculations, but since you say that 20 shots from a heavy rail gun did not have any effect (it is useless to shoot at it with pistols and lasers), then this means that there is no weapon that can penetrate such armor.
How to solve the problem (just select one of the points):
1) Go to the armors.rul file and reduce the obliterator’s armor to 60 points;
2) Go to the armors.rul file and remove the absorption of armor-piercing damage or laser damage, or even make it vulnerable to some type of damage;
3) Add EMP weapons to the mod and make the obliterator vulnerable to EMP damage (I did this, I just knock out the obliterator with a EMP grenade);
4) Add new types of damage from the FMPE addon (for example, plasma weapons can cause damage to armor, and the more shots are fired at an armored target, the less armor it has left, and this way you can remove armor and pierce thick armor even with a plasma pistol).