KADES as defined in the npcidentity.lua follows an ID of 2253 and therefore has to have a Mob ID set to 2253. You can use the mob_avail.txt to use the KADES sprite for your own custom mob so it looks like KADES. So since your ID is 2800 but your monster is NOT Kades simply add this line to your mob_avail.txt
Syntax: mob_id,sprite_id,equip #
Try this:
2800,2253,0
2800 - Your custom mob (new one) is set under a mob ID of 2800
2253 - Pull the mob sprite from the ID of 2253
Your mob should now look like KADES but has different database parameters (STR, DEX, DROPS etc).