If an enemy hexed with this spell dies before it would wear out naturally, the energy bonus triggers immediately. For this reason, with very high Illusion Magic (7 points or more for any increase at all), it can be worthwhile to cast this spell on a dying foe for a quick energy recharge. Unfortunately, the high cost and massive recharge time make it impractical as a primary energy management skill.
Using this skill with Mantra of Persistence will increase the snare time, but also prolong your wait for energy gain. Conversely, casting this on an enemy with natural resistance will decrease the snare time, but also shorten the wait for energy gain.