area // I think that a area would work best because... yea
          Monsters // just a little sub category 
               Entered(mob/M as mob) //calling the entered proc
                    var/mob/A = new/mob/monster/pie // this just defigns a new variable set to the key "A" and anything that is "A" is a /mob/monster/pie and it will always use A as that one mob, it wont make a new mob... yes pie is a monster
// you also can add in more monsters in it by making a new var which would look like this var/mob/B = new/mob/monster/pie, everytime you want a new monster in there you have to make a new varible and change the letter so the coding doesn't get confused
                    A.loc = M.loc // just brings that new mob to where you are, so it will poof right there
//If you used the previous information you will also have to add in a new proc right after ( or before) this line which should look like this B.loc = usr.loc and so on
// At this point you can make the mob step in some random direction incase you dont want it to be right under the users feet by using the step_rand() proc, for example
                    step_rand(A)
// you can almost do anything do to the fact that that spicific mob is represented by the variable A, even call other proc's to that mob in general like move(A) or death_check(A), whatever