I have put together a video tutorial on how to recognize and counter act the boss attack patterns:

A summary of the video:

• Side walking makes you inviincible against projectiles;
  
• All of his most damaging attacks require a short charge before being performed;
  
• His charged beams cannot be blocked, so side step and punish;
  
• His Circle of Doom can be blocked OR Trigger Guarded after the first hit lands;
  
• He has a death combo which MUST be Trigger Guarded;
  
• His cinematic beam can be blocked;
  
• When he runs at you, simply block HIGH. He has no running mixups.

I hope this guide can help you defeat him and understand his patterns!