I want to know if there are certain items this skill doesn't work on. Krong cursed my Fruitful staff with -3 armor, and when I tried to retranslate it, it kept saying "sadly you are lost in your own museum??"
Whenever you use this spell, it has a chance (I believe it to be 50%) to reduce the artefact value of the item by one (effectively giving it one point of bonus less after the re-roll) in addition to re-rolling the stat bonuses on it. When artefact quality reaches 0 or less, this spell can no longer be used on that item because "you are lost in your own museum". If you really, really want to use that item and to re-roll it, just krong it again and hope you'll get a blessing that would take you over AQ ("Artefact Quality") of 0.
Essence, get some sleep. Now excuse me while I'm going to get my dose of it (and I fixed the "AC" mistake).