[Cohen]

Well, I used it many times, especially with Forbidden Light.

I never saw an Undead getting killed, or someone getting that affliction in battle (well for the leaders at least).
But chicking random pick unit in the mid of the battle their stats were fine. I believe the spell is bugged, but someone else said that it takes time to make his action ... the fact is that other spells like this are far more effective since the round next the one they were casted (wrathful skies), while others seems to be very very slow ... the fiery one that should burn to cinder everything on the battlefield, doesn't set aflame anyone before at least 5-6 battle rounds after it has been cast, and when a mortal common national unit is set aflame it could die even if 2-4 rounds ...
For that time usually the battle has been ended.