Ina, the cheating heroine.

I think that Ingvar, like any other dwarven hero, can be defeated by a well-developed Necromancer. For example, using heroes like Lucretia, Orson, or Zoltan. In the late game, the dwarf will inevitably go for Light magic, unless he wants to surprise you with Armageddon and Pyrokinesis. If he goes for Light, it's best to take Zoltan to avoid duplicate core Light spells – Antimagic, Divine Retribution, and Resurrection. You definitely need to develop Darkness and Summoning magic. Darkness is obvious – for Domination, and in Summoning – the core spells are Phantom and Phoenix. I bet you don't use them, and therefore you don't know what a Phoenix under Vampirism or a Phantom Vampire with Soldier's Luck is like, especially if you combine it with Lucretia (I didn't want to say it... but you absolutely have to try it, you'll be pleasantly surprised). In addition to Summoning up to Master of Magic and Darkness up to Cursed Land, you definitely need to take Enchantment with Secret Knowledge, Luck with Soldier's Luck, and also Education with Master of the Dead, artifacts for spell power and mana, and, of course, more units to withstand while the Necromancer casts spells. In total, you get to level 27, and in the Outlands, with Education, you'll have at least 28, so it's perfect. I think it's all logical. I suspect that after this post, your opponent will hardly want to play against you again under these conditions, because, in my opinion, 5 months with two castles means that no army, no race can withstand the legions of Necromancers and the arsenal of magic of the Necromancer hero, which, in my opinion, will gather approximately – 60 Dracols, 350 Vampires, 1500 Skeletons, under 1000 Zombies, under 500 Specters, over 200 Liches, and over a hundred Deaths!