I ran a game with a friend recently and we wanted something a way to have a major showdown between one character and the slobbering god, and I came up with a very light system to give a little bit of uncertainty to combats. I also tried it in a more standard session but I repurposed it to simulate a board game and I found it worked well with no tweaks.

The way it works is based on Brennan Lee Mulligan's emphasis roll, where each combatant rolls 2d20 and takes the closest number to either 1 or 20, then whichever combatant has the highest or lowest number after that will take charge of describing how this phase of the challenge goes. If the number you won with is closer to a 1 you would describe a failure, mis step, or injury, and closer to a 20 would be a success. I haven't implemented a health or damage system with this because with my groups I found that we could just keep rolling until the challenge came to a narrative conclusion. I have yet to come up on a situation where a player lost against a kith but I'm not particularly worried about that situation given that death isn't a necessary conclusion.

If anyone does want to add a health system I have been playing around with the idea and I think that it could be easily implemented by picking a low number (or rolling one) to represent how many succeses from the opponent are needed to win the challenge, but I haven't use this so let me know if you do.

If anyone has any suggestions for how to improve this I would love to hear them, and let me know if you use this system in your own game!