Heroes 3.5: In the Wake of Gods Portal > Wraith Bomb (Trick)
Wraith Bomb (Trick)
Wraiths can be useful after all! Send out waves of expendable heroes against a dangerous invader, each with 7 1-Wraith stacks, with the aim of reducing his spell points. You will need lots of extra gold of course to make this work.
This, of course, works better against the AI than it does vs. another human and is countered by Destroy Undead, but if you have the Pendant of Death…!
And even getting your enemy to cast Destroy Undead over and over is going to cause him to lose spell points.