I think the Talos boss fight is. bugged. I rush him early, jump on top of him, and break all of the crystals. I heard there's an achievement for defeating him before he gets to Volcanic Island Camp, so I'm trying to do this.

When I get to the last crystal, it's immune. Even after he passes the Volcanic Island Camp, I'm hacking away at this crystal 100+ times and nothing. The other ones break in about 5 swings. What am I doing wrong? Is my game bugged from progressing?