How to Stop Griefing Inside Your Region (Flags and Deny Messages)
Understanding Flags
Flags control what happens inside a region. Each flag has a state: allow, deny, or none (inherit from parent). Set a flag with /rg flag <regionname> <flagname> <value>. For example, /rg flag mybase build deny stops anyone without build permission from placing or breaking blocks. Common protective flags include pvp, tnt, fire-spread, lava-flow, mob-damage, creeper-explosion, use, chest-access, and interact. Setting build deny is the broadest protection; combine it with interact deny to stop buttons, levers, and doors from being used by outsiders.
Greeting and Farewell Messages
You can tell visitors what is happening when they enter. Use /rg flag <regionname> greeting <message> and /rg flag <regionname> farewell <message>. Color codes with the ampersand symbol work in most setups. This is useful for warning players that PvP is disabled or that building is not allowed. To check every flag currently set, run /rg info <regionname>. To remove a flag and return it to default, use /rg flag <regionname> <flagname> none. Flags apply only inside the region bounds, so overlapping regions can have different rules.