hmmm...
I was thinking that we have to be mud-proof to go into the Phool and Jeth, etc..
lightening-proof to be in Alakol
acid-proof to be in llemskie or llemskie deeps
fall-proof to be in Groddle Forest
etc, etc
and every one of those 'proof' comes as a reward with a very hard quest that also require a certain level.