UOR based PVP with additions to various skills to provide a wider range of templates that can compete.
In a nutshell:
Stun Mages: Wrestling + Anatomy allows Stun Punch attack
Thiefs: Wrestling + Armslore allows Disarm attack
Evaluating intelligence >= 80 + Anatomy >= 80 accounts as wrestling (old OSI UOR based mechanic)
Alchemy gives bonuses for potion usage (effect strenght and duration)
Tank Mages: All melee weapons have a nerfed version of the “insta hit”
Lumberjacking: Gives a bonus when using an axe
Bowcrafting: Gives a damage bonus when using a bow
Carpentry: Gives a damage bonus when using wooden non-ranged weapons.
Mining: Gives bonuses when using hammer picks and war axes
Peacemaking: Along with taking the victim out of war mode, it also disturbes magical spells