60b52515_ons_Flags___EngineHub_org_Wiki__Description
[Flag] deny-spawn [Default] unset [Default Group*] N/A [Type] List [Description] 
Set mobs that can't spawn within the region. From console or ingame: /region flag [id] denyspawn Skeleton,Zombie,Creeper,etc . In config file: deny-spawn: [SKELETON, CREEPER, ZOMBIE, ETC]
WorldGuard/Regions/Flags - EngineHub.org Wiki
Description