In 2013, a teenaged Isabelle Rezazadeh was living at home, studying production tutorials online. Three years later, Skrillex and deadmau5 were putting out her unorthodox take on EDM—a grinding, slow-motion techno style called “midtempo,” although that name barely comes close to capturing Rezz’s snail-paced menace. Her early tracks, such as 2016’s “Purple Gusher,” have throbbing arpeggios fit for a zombie film, setting the stage for gorier glories to come, like “Falling,” an anguished collab with post-hardcore shouters Underoath, or the ethereal dubstep of “Into the Abyss,” with Zeds Dead. Rezz is discovering new frontiers in rave’s darkest corners.