Well, basically if we take higher darkness, we'll be left with only the berserker, and that' same after so much trouble learning eagle for the witches.

Play the late game on large maps with plenty of secondary towns of different races. Build your guild + Dragon Utopia in them. And let the enemy rack their brain over which magic you'll arrive with — Light, Darkness, or Chaos. For an Orc, this is just clay.

hit and run, well it's really humiliating(((

A war of attrition knows no such word. However, hit and runs are countered by anti-runner heroes

But let's return to Chaos and the option mentioned above: rune set + Elemental Fury. With 2 castles and expert racial skill, this is +200 damage to almost all your spells (since you can choose who and what to cast on) and +200% to all your troops with a probability of from 25%. To me, that's cooler than the Elf Avenger.

1. Choose Sinitar or Erin
2. Level up Elemental Fury (the most useful skill build СА among all races, imho)
3. Level up Education with Attraction and perks for stats. Level up Attack with Speed Magic and Cold Steel (there is an option with Defense, but that's more of an alternative and only for Sinitar)
4. Collect the rune set
5. Collect the knight set
6. Other artifacts as available; luck must be brought up to 5.

If you get lucky rolls for morale (for hero promotion), luck, and elements, there's a chance to take down absolutely anyone. The situation certainly doesn't look hopeless, rather artifact- and RNG-dependent :-)
In battle, the following nuances should be remembered:
1. Elemental damage is twice the base. This means simply spamming Shock is not an optimal option. The spell and target should be chosen carefully. As well as targets for unit attacks.
2. Additional spell effects like reducing Defense or increasing same damage received will often be more important than direct damage.
3. Each cast with elemental damage on a stack changes its element. Sometimes it makes sense to hit a crowd with Meteor Shower if they have inconvenient elements.
4. Mass Haste at the very beginning of the battle will later provide the opportunity to cast more frequently.
4*. When playing against an orc, it is important to remember that different spells are weakened differently by the dampener; for example, Chain becomes equal to Shock in damage even only for the first stack.
5*. Against an orc, it's important to successfully swarm the cyclopes. Stopping Cold and Fire Lord greatly ease this task.