Play against Necropolis.

Tell me everything you know about the Orcs vs. Undead matchup!!! Their weaknesses, which skills to take, the strategy (but don't just say to prolong the game) for the battle itself, which hero is better, and so on... Someone just said that Orcs are nothing compared to the Undead, and I want to prove them wrong!!! This really got to me!!! And since I haven't been playing as Orcs for very long, I don't know all the pros and cons of this race! And he's been playing as the Undead since Heroes 5 came out(( but from my observations, he's not a very good tactician, so we need to take advantage of that!!! Therefore, please write everything that will help me in the game... (I want to note right away: we will be fighting on the largest map possible).

The goal is clear - develop faster. Take Hagge with Centaurs or Argath, who needs to quickly get the Path of War. Due to mobility, you can outpace the Necromancer in level and resources. Don't prolong the game; you need to kill the Necromancer no later than week 6, even on XL, and preferably on week 4-5.

And everything else is correct; the maximum map is almost a victory. Only one small "but." It is possible, although difficult, to rush with Orson on week 4; for an unprepared Orc, this is death.

For the Orc, prolonging the game on a maximum map against the Undead is equivalent to suicide.
1. Even with maximum Magic Resistance, Dark Magic will still be quite effective. Even a simple Slow will remove 30% of initiative, and then there's Banshee's Cry (and if there are at least 2 items from the racial set, it's game over). Magic Resistance is effective against Chaos, but not against Light or Dark.
2. Summoning will still be relevant for a long time, but not Phoenix, but Sky Shield on Vampires + Vampirism. It's terrible.
3. On a large map, secondary settlements are easily captured, and this is the most fun. You build a Magistrate in them and upgrade the castle to level 4. There will be enough money from the castles to buy reinforcements, and then convert them into Undead with caravans. When the Necromancer starts producing 30 Vampires per week + raised units, Fury won't save him.
You need to kill the Necromancer before he sets up an increased production of his own troops.