Also, in Doom, difficulty only changes the amount of monsters, not their damage. Damage is determined by a dice roll, so for example, the mancubus fireball "rolls" an eight-sided dice, so 1-8, and whatever number you get is multiplied by 8, so it can deal 8-64 damage, IIRC. The pistol and chaingun will "roll" a three-sided dice, so 1-3, and then the damage is multiplied by 5.

The Mancubus fireballs always do the same thing:
Volley 1 - one fireball towards you, one to your right
Volley 2 - one fireball towards you, one to your left
Volley 3 - one fireball to your right, one to your left, but at a shallower angle, so if you are too close both can hit you since the projectile hitbox is so large!

If you are using the SSG, then typically you only need to worry about the first volley because you will stun him with the SSG. So, you stand somewhere where you have room to strafe left, and while blasting as fast as you can, you strafe left for his first volley. If you need to dodge volley 2, you strafe right, and if you need to dodge volley 3, you run backwards.

cool, hard af