Important reminder - combat changes don't work properly in custom battles.

Combat is designed to be about x2 longer than vanilla balance, so about 10 minutes on average for a battle to wrap up. Units deal way less than half damage however, the cause for battles ending is increased morale panic. You can cause chain routs by getting a couple units to shatter at the same time. Focus on one flank with your strongest units to batter them, hit them with ranged, spells and rear charges (all of them each apply a different morale penalty) to cause a rout. Don't spread your damage out evenly. If you don't successfully chain rout the enemy and try to individually kill each unit battles will last much longer. Battle length can vary a lot depending on what you're fighting though, stacks of chaff will rout even faster than vanilla while elite armies can hold the line far longer.

In vanilla, ranged units have very good accuracy by default, so much so that buffs to accuracy aren't really noticeable. You can have a unit of rank 1 peasant archers firing on a single foot lord in combat and each arrow will perfectly arc through the air and land directly on the head of that lord. Accuracy is much lower in this mod so rank 1 units will have trouble hitting an entire unit at distance. With lower rank units try firing into large melees where they will have trouble missing anything, don't get into max-range archery duels against another single ranged unit (unless that unit equally sucks and you feel like wasting ammo).

Elite cav is rebalanced to be the most powerful thing on the battlefield compared to infantry or ranged, but charge speed drops dramatically as a unit gets exhausted so it doesn't last. Cavalry is harder to use than passively sitting back with infantry and ranged, gets an entire unit classification (spearmen) designed just to hard-counter it, and is less effective in sieges. The reward for bringing elite cavalry is that it's more effective when used properly.

Towers hit much harder and also apply a strong slow to units they hit. Siege towers hard counter them. If you run in with ass ladders without using artillery to destroy their defenses first you will suffer heavy casualties.

Some other random notes:
* Undead rely on their wizard characters to remain intact. Kill the wizard to make them fall apart
* Individual cav models have a small chance to rear up and stall when charging into braced spearmen, so... don't do that
* Charge bonus lasts 30 seconds instead of the vanilla 13 seconds, to account for the slower combat
* Gunpowder and warp lightning artillery has a very small chance to misfire and explode. It should not be happening enough to effect balance, it's mostly for flavour. Campaign health for artillery is based on the number of men surviving, not the number of artillery pieces, so misfires won't carry over to campaign
* Necromancers and Ghouls are not undead
* Menace from below don't disintegrate. You're going to need it with Skaven, with the morale problems they have