Discussion about Dungeon (Dark Elves).

I had a question. I was playing as Wing against Leto. Our levels were roughly the same, and I had battle unicorns, the Forgotten Hero's armor, and a luck perk that reduced magic damage. As a result, Leto's ability to poison all enemy units with plague at the start of the battle didn't work on a single unit. Is this even possible? Or was it some kind of bug?