Berserker is easier if you stick close to him. If you are close, not much further out than his long red cone, he will not axe throw. Without axe throw, he only has two moves that are concerning: his exclamation w the long red cond, and his small bright red spot. Both of these are directional and will likely one-shot you or hit you very hard. To fight him, stick close to him. When he does his exclamation mark, get ready for his long cone. He stops just before his attack. Get behind or to the side of this. Same w his red dot, which can be quite difficult to see if too many affects are going on. The red zones are easier to see solo. When it is difficult to see anything, I just stick close to him and try to be behind him at all times.