The Volatile Ammo mutator replaces all the ammo on a level with an exploding version. When the ammo pickup is shot, it explodes like the ammunition type it contains.
This mutator does not work when used with the Arena Mutators because they don't allow the ammo or weapons to be replaced.
The Team Beacon places an icon above teammates during team games. The sprite doesn't scale so well when the sniper rifle is used. The icon is a 3d world object so it will, at times, intersect with the world geometry.
And lastly the Volatile Weapon mutator causes your weapon to explode after you die leaving no pickup.