 She edited episodes for the sixth season of "Buffy the Vampire Slayer", served as an assistant editor for "Angel", and has edited various episodes of "Firefly".Lassek is a frequent collaborator of Joss Whedon, having edited his first feature-length film "Serenity" and the Marvel Cinematic Universe films, "The Avengers" and "" (which she co-edited with Jeffrey Ford).She has also collaborated with Drew Goddard, having edited his films "The Cabin in the Woods" and "Bad Times at the El Royale".