Rand: This trigger will randomly set off the mprog according to its percentage. The pattern is a number, which is the percentage you wish the mprog to trigger. This must not be set higher than 40, because it's checked against once every 4 seconds. Be aware that this means that even a random 1 may rarely happen twice in a row, so it could fire again four seconds later, or four hundred seconds later. Random triggers do NOT run while the mob is fighting (use fight triggers for that), nor do they run when no one is in the area unless the mob has update_always, which you're not supposed to use. For most things (e.g. a mob occasionally talking or something), you probably want to use random 5 or so.

To set this trigger, use the following syntax:

addmprog <vnum> random <percentage #>

Example: addmprog 3001 random 15