After looking at the bin files I want to point out that +15 is actually less likely than +18 (same goes with +5,10 and 20) how is it that all of these people who cant afford scrolls, lvl 7 euphoria, lvl 7 equality have +15 rings?
Because some tier 2 GM decided oh there is nothing wrong here he just has 12 +1 tickets in his inventory asking to make 4 rings +15 sounds legit alright then!