I didn't like this at all. 80% of success in a run is determined by pure random. In the end, if your characters aren't fully healthy, if your weapons aren't the best, and if you don't have consumables to repair your weapons, you're guaranteed to lose. Why even bother with the ability to restore 7+ hp if the maximum hp you can have is only 8?
I'd allow players to carry 2-3 consumables per character at a time, so that success depends more on the player than on randomness.