The BFG is good for fighting the Icon, but you should use the Crucible when it comes to regular demons who might give you serious trouble, like Tyrants or Barons.
Both arenas have BFG and Crucible Ammo in no small quantity. If you haven't destroyed the hands yet, now is a great time to pull out your Super Shotgun and retaliate! A close-range attack will do a lot against it. The Icon's punches are very fast - if you see it winding up one, immediately dash to the opposite side of the arena. Think of it like this: if it's not trying to punching you, it's probably winding up a projectile, or doing the little Jedi mind trick-gesture it does to summon more demons. Most of the Icon's attacks are huge punches or fist swipes, but it can also shoot projectiles from the pentagram floating above its head, summon meteorites, as well as blast streams of fire from its palms. The Icon's armor doesn't really give away when it's damaged, but its body will visibly degrade and be destroyed as you shoot at it. BFG 9000 shots are suitably devastating in either half of the fight, doing huge damage and in some cases able to destroy a section of armor/body instantly. If it doesn't do that, you can move onto another part. If you're not sure in either phase if you're damaging a body part or if it's already destroyed, it should glow/flash red whenever it takes damage. Here's all the best tips and tricks for dealing with this super demon. Now you know the process for killing the Icon of Sin, we can get into the details of the best way to do that. | Joel Franey/USgamer, id Software/Bethesda Software Icon of Sin Weaknesses You need to destroy the Icon's armor first. There'll also be a counter on the left-hand side of the screen that tells you how much of the demon's armor/body you've destroyed, as well as the health bar at the top. Don't bother attacking this if you haven't destroyed all the armor yet, that field still protects it. It's pretty obvious when you destroy a piece of armor, as it'll visibly explode and shatter, revealing skin wrapped in a thin field of red energy. You'll have to destroy all of the armor before getting to work on the the Icon's body, both of which are divided into eight sections: Like mentioned, the Icon is a boss fight where you'll have to destroy the Maykr armor before killing the demon itself.