While folktonica innovator Juana Molina has always explored unease, even her longtime fans may be surprised by the all-consuming darkness of Halo. Gone are the gorgeous acoustic melodies and gently humming rhythms, replaced by abstract swirls of skittering beats and electronic drones that rumble with dread. Her trademark vocal experiments remain, but they’ve grown ominous. She pitch-shifts herself into an unearthly choir on “Sin Dones,” and layers ghostly harmonies over the rattling groove of “In the Lassa.” Despite its forbidding surface, Halo also flickers with moments of fleeting beauty, and the slippery hooks are captivating in their strangeness. Lock into its eerie pulse, and it’s another bewitching trip.