Another option is to set effects on an item with a set 'sleep' command on them so they refresh and continue constantly. Setting the items level requirement to 99 would give you that desired requirement as well, but of course, you're assigning it to an item then and that takes up a slot or inventory space.
3000,Item_Name,Item Name,4,20,10,1,,1,,1,0xFFFFFFFF,15,2,136,,1,0,,{ while (isequipped(3000) ) { specialeffect2 700; sleep2 1600; specialeffect2 500; sleep2 1600; } },{},{}
So this equips in the accessory slot and refreshes an effect at certain intervals (The effects in this script are actually random, so don't rely on those to even be working effect numbers), and the sleep sets a refresh rate (should be adjusted to the effect) so that if a new player warps on to the map, they'll see the effect appear after a set interval of time. It isn't perfect, but it's fun to play with and you can use it to give your GMs a special aura from players or unique to each GM entirely.
Hope this helps, ~Azura Skyy