Barbarian magic suppression skills...

Maybe it's because you used Darkness spells on them a lot, and the opponent didn't have Anti-Darkness spells;)? Because with such a Spell Power, any Darkness spell (if not suppressed) sticks "forever."

We played that battle twice - with Darkness spells and (just for fun) without them.
With Darkness spells, the Orc lost without a chance. Without Darkness spells, I lost, but they didn't manage to defeat the Phoenix. They just tore my army apart. Strangely enough, I had full Darkness spells, but not full Summoning spells. I didn't have Walls or Hive. Maybe if I had blocked with walls, I could have won without Darkness spells...

Therefore, I stick to my opinion - Anti-Chaos and Anti-Summoning spells quite severely reduce magic. But Anti-Darkness spells - not so much.