The most powerful warrior.

But didn't you have only Dark Champions, and Armageddon also damages your own units.

Probably, there was no armor penetration, otherwise this ability is ambiguous; it can hit your own units, just like with Armageddon.

but skeletons are hidden - zombies and incorporeal units will protect them

but they have low initiative, and they deal little damage, so heroes can cast something with chains on them, and when the hero is Erin, the witches also shoot during the spell :D So your skeletons and zombies are not a problem, only the ghosts will be a hassle.