Discussion about Sylvan (Wood Elves).

Well, I quickly equipped Ossir with Combat skills, Armor, and Boots.
Total: 15+30+20+10=75% resistance. 7 units of Supreme Druids on the enemy hero's auto-battle. Sometimes they cast spells, sometimes they shoot. Not a single deviation on 10 Horns.
And Mages - yes, they are more dangerous. I remember they either cast Fireball or use Fist.
I mean, the Archmages.

Funny. I tested it. Indeed, sometimes they shoot, sometimes they cast spells, but still, sometimes they hit the resistance. I saved the replay just in case. In general, it's very strange; on the test server, I saw completely different behavior in the game. And here, it seems like you absolutely need Marbas with 100% resistance so that their spells are grayed out in the spellbook.