Triptykon have shared footage of themselves performing Celtic Frost’s “Rex Irae” during their special orchestral set at last year’s Roadburn Festival. That set featured a three-part “Requiem” composed of “Rex Irae” off Celtic Frost’s “Into The Pandemonium,” “Winter” off Celtic Frost’s “Monotheist,” and the recently finished “Grave Eternal.” A live release featuring that performance, titled…