Three times in a row I cast mirror walk with rolls that beat the DC and yet they failed. It looks to me like there's a public roll that determines if you successfully make the trip and a secret roll that says what happens in the mirror realm, but you've
included not successfully getting there in the possible outcomes of the 2nd roll. The roll that comes after the roll to see if you get there. So the situation is that we have a spell granted to clerics by Gods that has double the chance of failure compared to the regular teleport made up by humans, at a higher level than teleport, and the same cost in gold.
Three castings of a spell granted by a God shouldn't cost me 2550 gold and 37 points of damage to leave my character standing exactly where she was when she started. I would suggest making the initial roll be the only determiner of whether or not we get to our destination and the second roll only determine whether or not we're attacked on the way.
Thank you for coming to my Ted talk.
screenshot in spoiler
