Tetrarch, which opened for metal band Atreyu’s 29-date Baptize tour, got a visual assist from LD Ryan Pervola. At the 1,400-capacity Roxian Theatre near Pittsburgh, Pervola served up an added dose of luminous intensity from the venue’s house rig, which included Maverick MK2 Wash and Rogue R3 Wash fixtures from Chauvet Professional.