Orcs vs. Humans

I believe that for an Orc, a buffed light spell can sometimes be scarier than a dark spell. A debuff on dark spells is more effective than a debuff on light spells. Here's why: dark spells have an effect if they last for an average of 5-8 rounds (therefore, a debuff on dark spells will have a greater impact on the outcome of the battle), while light spells only need 2-3 rounds to destroy a good half of the Orc's stacks (and here, the spellcasting stat of a hero from Haven is not that important). Therefore, a debuff on light spells is rarely used.