The effects of haunt are inconsistent, causing damage randomly. The low chance of its effect taking hold decreases its usefulness further. The fact that this Psynergy only attempts to inflict the haunt status and nothing else, it is mostly useless. Normal battles don't last long enough for the haunt to do much damage, and it hardly ever works on bosses. When used by an enemy, however, the fact that haunt's effects are difficult to remove (only Salt and Tonic can remove it in battle) and the fact that it can deal significant damage to your Adepts, greatly increases its efficiency.