Fun fact: When comp capes were released, unlocking claws of guthix was the one requirement I was missing from obtaining the cape. I wasn't sure if I had done it or not in the lead up to release, so I had to go quickly do that before getting my cape!
I do basics until tangle attack, use wild magic when he tendrils me, follow it up with a claws of guthix and continue using basics.
During first beam I meta and get up to high adren, asphyxiate asap (hopefully before he does the tangle attack), then wild magic, tendrils and a deep impact if you can get it in... Every beam after that, just do a few claws of guthix but try to keep high adren for phase 2.
Unslain Bosses - Clan