On his latest mix-tape, Philadelphia-based Brit DJ Trace places deadpan Blade Runnerish utterances over apocalyptic stuttering and clanging “techstep” beats. Programmed by Trace, fellow Metalheadz DJ ED Rush, and others, this minimalistic sci-fi soundscape is alternately fascinating and tedious. There is hope for the former, however, at “Dementia,” an all-night jungle/drum ‘n’ bass affair where Trace and Rush, the latter making his first U.S. appearance, will unleash three hours of “tag-team terror” on an admittedly suspecting crowd. With D.C.’s DJ Slant and Karl K, Philly’s Method One and Kaos, plus guest toasters MC Rhymetime from London’s Kool FM, Philly’s MC Dub 2, and a separate DC Dirty Crew house-music room. At 10 p.m. at the Skyline Club, 1350 Okie St. NE. $15. (202) 736-1714. (SK)