Force drain/Legends

Force Drain is a Dark Side equivalent of Force Healing, except that the user drains the target's Force reserves to fuel the regenerative process, or to replenish their own strength in the Force. Greater aptitude allows exceptional drainage speed and the ability to drain multiple people at once. A very few (possibly Darth Nihilus alone) have taken this ability to such heights that they can feed on entire worlds at a time. Emperor Palpatine fed off the inhabitants of his retreat world of Byss collectively with his dark side adepts.