For Battles, it was always going to be downhill after a record like Mirrored; a strangely hypnotic and danceable collection of math rock songs that let the group kick in the door, guns blazing, announcing to the world that Battles were a fully formed and ready to rock. While recording their follow-up, 2010’s Gloss Drop, the group lost their lead singer and were forced to bring in a number of guest vocalists to fill the void as well as dropping vocals from a number of the tracks altogether. This schism of sound didn’t do the album, admittedly very good, many…