Doesn't work, well it does, it just deals 1 damage. Always
Reason being, the ability works based on shifter levels, 1d4 damage per shifter level, but since the imp has 0 shifter levels, it just deals 1 damage.
Could this be changed to actually use character levels rather than shifter levels? A quick-fix might also be giving the imp 20 WIS or something similar.
*bada-bada bump*