I also saw them a couple of weeks ago with Mastodon closing, but I honestly think it would have worked better the other way around. It felt like the crowd used up all of their energy on Gojira and didn’t have much left for Mastodon. I saw quite a few people leave early. For what it’s worth, I was there mainly to see Mastodon, but Gojira ended up being the highlight for me. They went hard.