Haven vs. Necropolis

I've always questioned the usefulness of the Agony skill.

Here's a simple example: the opponent has Royal Griffins (or another unit with infinite counterattack). Using Agony and attacking this unit with all our forces gives us 7 Agony procs in just our turn. Furthermore, when playing as Inferno, you can also apply Berserk, adding +1 proc. What's especially pleasing is that the damage is dealt BEFORE the action is performed, meaning we effectively deal additional Dark magic damage, and the counterattack weakens with each hit.