The wisp projectiles bob up and down as they fly and lack the ability to detect and avoid the terrain. As a result, wisps will hit the ground on a regular basis.

This becomes a massive problem when attacking a target from above, where the wisp's downward motion causes it to undershoot it's target and collide with the ground the majority of the time, making the spell virtually useless.

Even with an easy target, the spell is unreliable on anything other than perfectly flat terrain and altogether doesn't feel like a useful combat spell even for dedicated healers.