Massive Attack spawned dozens (hundreds?) of imitators in the ’90s while pretty much writing the book on trip-hop. It’s hard to imagine the genre’s touchstones—Tricky, Portishead, Morcheeba—outside the Massive Attack shadow, and it’s hard to describe Massive Attack’s hazy, ominous sound without invoking shadows. The group fought pretty consistently after 1998’s Mezzanine, with different members shifting in and out and the group taking seven years off between records, but they appear to be solidly back together for 2010’s Heligoland. Packed to the gills with guest performers like Damon Albarn, TV On The Radio’s Tunde Adebimpe, Hope Sandoval, trip-hop diva Martina Topley Bird, and perennial Attack favorite Horace Andy, the record’s an absolute welcome return to form.