Let's continue with these micro-optimizations.
You can destroy liches on slow elementals/golems/gargoyles if you have a catapult – it will splash damage on them, but nearby non-living creatures won't be affected.
That's a cool trick.
I'll share a well-known fact that I recently learned:
The damage of a ballista is calculated as (hero's attack + 1) * 2 - (hero's attack + 1) * 3, and the Archery skill is also taken into account.
That's why Gurn is the best with a ballista, as he is a Barbarian and gains attack on the first levels.