is_npc Do NOT remove this flag. Your mud will crash the next time that mobile loads.
sentinel Mob does not wander out of the room, mob will not quest
scavenger Picks up loose eq in rooms
remember Will remember those that have fled from it
no_flee Does not allow characters to flee from that mob
aggressive Will auto-attack any who enter room
stay_area Will not leave area
wimpy Mob will flee if hurt
pet Mob may be sold as a pet
*train Players may gain levels or do statraises at this mob.
practice Players may practice spells at this mob
*mercenary Mob will hunt and attack players (Does not work with stock money system in  4.3.1)
heal Mob will sell healing spells to players
*adapt Mob will modify a weapons level and stats so that a lower level player may use it. (Does not work with stock money system in 4.3.1)
undead

Will not aggro on vampires, if the mobile is a shopkeepers it will sell to vampires. Do NOT use this flag with spec_fun_executioner!!

*bank Players can deposit, withdraw or exchange money with this mob
*no_body Players can not use certain skills on this mob. (Only backstab in stock)
hunter Not used
no_mind Some Psionic spells do not affect this mob
postman Players may leave notes with this mob
rewield Mob will equip best weapon in inventory
reequip Mob will equip best armor in inventory
intelligent  Mob will recall out of battle or leave no corpse. They also do not repop in area (they hang out in the NPC Party room.. heh). Use this one carefully. (Disabled in stock)
vampire Mob will not quest and leaves no corpse
breeder Not used
solo Mob will not assist other mobiles (*unless brawled) but fights much stronger on its own
werewolf

inactive for the most part, but mobs will sell to wolves.

mount Mob may be used as a mount
no_blood   Mob may not be the subject of certain spells