How to Set Global Server Rules with WorldGuard
Using the Global Region
WorldGuard has a special region called __global__ that covers the entire world. Flags set here apply everywhere unless a specific region overrides them. This is the fastest way to disable a mechanic server-wide. For example, /rg flag __global__ pvp deny turns off PvP everywhere, /rg flag __global__ fire-spread deny stops fire from spreading, and /rg flag __global__ tnt deny prevents TNT from being primed. You can also disable lava-fire, lightning, snow-fall, ice-form, leaf-decay, mob-damage, and many others.
Overriding Globals in Specific Regions
Because region flags take priority over global flags, you can re-enable a mechanic in one area. If PvP is denied globally but you want an arena where it is allowed, create a region around the arena and run /rg flag arena pvp allow. The same pattern works for build, use, and every other flag. Remember that none means inherit, so a region with pvp none will follow the global setting. Use /rg flags to list every available flag and its current value in the global region, which is a quick way to audit what your server is doing.