Fan-filmed video footage of OPETH's June 2 performance at the FortaRock festival at Goffertpark in Nijmegen, the Netherlands can be seen below.
OPETH is expected to spend much of 2018 working on material for the follow-up to 2016's "Sorceress" album for a tentative 2019 release.
Asked by Ireland's Overdrive last November if fans can expect to hear more experimentation and evolution from OPETH in the future, guitarist/vocalist Mikael Åkerfeldt said: "I'm not one of those guys that sits there with calendar thinking, 'Okay, I need to do this kind of album now and then I have to do that kind of album later.' I really like not knowing what is happening or where the direction of the music is taking us.
"When I was starting out, I was just really happy to be in a band and playing music," he continued. "I was more inclined to look forward with things instead of enjoying the present, which is what I tend to do now, with my music career as well as my private life.
"Musically, I love being in a position of when people ask me, 'What do you think the next album is going to be like?' and I'm there thinking, 'I really don't know.' In fact, sometimes I still don't know until the whole thing is finished. When I write one song a certain way, the next song might be completely different, which I love."
Mikael also talked about OPETH's musical evolution over the years, saying that he is "very happy with where we are at the moment. What happened with the change in style was not really a big thing for us, especially for me, because I've been consuming music that's different to death metal for a very long time," he explained. "I'm sure it was a little drastic for the fans.
"When we released 'Heritage' , it really was intended to open up a few more doors for us, and now as a result of that, I feel freer when I write. I could technically write another 'death metal' record, but I'm elsewhere right now. So, I'm not really sure if we have discarded the shackles, but I know that there are fans out there that are not with us anymore. But I want to play music that makes me happy, and right now I'm feeling very free with everything.
"As a band, we got really tight after the tour cycle for 'Heritage', which was a very long tour, which we actually started doing before the album was released. We had a considerable portion of the album in the live sets and that was just a trial by fire as we were evolving and playing something different to audiences before the album was released. It really showed a different sensibility to this band that's been there before but we never really showcased it. That was a huge learning curve for us."