So in my weekly game this last weekend my players ran into an Illusionist. About half way through the combat she cast Mirror Image on herself as the melee moved in closer to her. Only issue was when reading the spell it wasnt clear how to resolve whether they hit an image or the real person. the wording directly from the spell says "Whenever you are attacked or are the target of a spell that requires an attack roll, there is a possibility that the attack targets one of your images instead. If the attack is a hit, roll randomly to see whether the selected target is real or a figment. If it is a figment, the figment is destroyed. If the attack misses by 5 or less, one of your figments is destroyed by the near miss".
This wording caused some confusion both for myself as DM and my players as to how to resolve, in the end I had to just wing it with a d100 roll. Just wondering how other GMs or players have dealt with this spell as it seem like its missing something?