you have to kill the cognitor (the tall ahh thing that will chase you if you take too long on a floor), crimbo update was introduced at december last year, I think it's unavailable on the newer version?
the stones (the diamond shaped thing) is an attack rune or something, I forgot the name. It can be used to damage and kill enemies by holding your attack button until you see the charging animation with black particles. Each hit deal 1 damage. You can also get an equipment that will make your basic attacks deal damage, like the claw, the knuckles, the boxing gloves, etc