You are getting way ahead of me
I don't have AC in for mobs yet. It actually is in the code about 90% - I've been slipping it in a little at a time - but isn't implemented yet. As is the case in any change like this, we will test it on our server first before putting it in the code.
There will be an AC column in npc_types, but it isn't there yet. It will go through the same code as it does for players. Currently, for players (and therefore eventually for mobs) hits are reduced by a random value between 5% and 10% of the total AC. This will be changed as we try it and adjust it.
So a hit of 350 on a target with AC of 1500 would be reduced to a hit of 200-275.
The big controversy among developers regarding AC is this: should a hit for the max amount ever be achieved? As an old AD&D player I satnd on the side of "no". Armor should, in my opinion, always provide some protection, just as it would in real life. Others believe that there should be a random possibility that it should. I understand it does on eqlive. Since this is an emulator, if that is true, it should here too. (Although it won't on our server <grin> )