I threw this tool together last night to calculate the odds on skill challenges:
http://76.79.193.188/SkillChallenge.php
This will likely reinforce many of the same conclusions people are coming to in threads like http://www.enworld.org/showthread.php?t=229919&page=1&pp=15 but I hope you'll play with it yourself and come to your own conclusions.
Some observations from examining the rules as I was doing this:
1) The most obvious reason that skill challenges get so difficult is that the distribution of success and failure patterns on the dice is distributed along Pascal's Triangle. Since we're getting only a tail of the triangle rather than half of it, this gets more punishing as the difficulty of the challenge rises. Even if you have high skill levels, factorials (making up the individual cells of the triangle) grow faster than exponentials (making up your odds of each cell), so higher complexity challenges will be very likely to fail the party.
2) The easiest way to bring the system up to a base 50/50 success chance is to get the party to an averaeg skill level and other die modifier of 9+level adjustment, and give them a way to earn a number of failures forgiven as the complexity+1. The failures forgiven moves our permutation distribution back to the center of Pascal's Triangle, and the 9 skill gives them a 50% chance of success per roll. I like this approach because it doesn't require a rewrite of the rules, just a new tradition in skill challenge design. Skill challenges will take about 50% more rolls to resolve this way, but that suits my tastes as a storyteller.
3) Using healing surges in place of failures that can end the challenge for half the checks (as in the sidebar on DMGp76) also gives a 50% success chance for the party at ~9 skill.
http://76.79.193.188/SkillChallenge.php
This will likely reinforce many of the same conclusions people are coming to in threads like http://www.enworld.org/showthread.php?t=229919&page=1&pp=15 but I hope you'll play with it yourself and come to your own conclusions.
Some observations from examining the rules as I was doing this:
1) The most obvious reason that skill challenges get so difficult is that the distribution of success and failure patterns on the dice is distributed along Pascal's Triangle. Since we're getting only a tail of the triangle rather than half of it, this gets more punishing as the difficulty of the challenge rises. Even if you have high skill levels, factorials (making up the individual cells of the triangle) grow faster than exponentials (making up your odds of each cell), so higher complexity challenges will be very likely to fail the party.
2) The easiest way to bring the system up to a base 50/50 success chance is to get the party to an averaeg skill level and other die modifier of 9+level adjustment, and give them a way to earn a number of failures forgiven as the complexity+1. The failures forgiven moves our permutation distribution back to the center of Pascal's Triangle, and the 9 skill gives them a 50% chance of success per roll. I like this approach because it doesn't require a rewrite of the rules, just a new tradition in skill challenge design. Skill challenges will take about 50% more rolls to resolve this way, but that suits my tastes as a storyteller.
3) Using healing surges in place of failures that can end the challenge for half the checks (as in the sidebar on DMGp76) also gives a 50% success chance for the party at ~9 skill.
That's why I wrote it.
