well alot of things in the game trigger randoms. simply walking from no multi to multi triggers one. it also is the action around u. i was with this one person who hasnt moved or talked and when i said something HE got a dwarf. when i was trainin on blues on my pure, 95% of the time when i watchtower tele i got abbyss, only once did i get another random(quizmaster. first one ever) it seems some ppl get some randoms alot more than others. i have only had 1 mime within 2 years of playing and on 3 of my other chars ive gotten them pretty early on playing. submit ur theory to jagex and see what they say. but u need to remember they r anti-macroing program(for lack of better words)