So if the high end of the d20s are reserved for explosions, usually just 20 on both dice, but there are situations that change that, how do critical successes work? It’s quite simple, if you get a result sufficiently higher (or lower) than the target number then that counts as a crit. So maybe your attacking someone with a defense of 10 and need to get 20 higher than that for the crit. With no modifier that’s a 15% chance to get the success at all and a 0.78% for a crit.
Obviously this is a pretty hard to hit target.
With a +10 to your attack though, you’ll now be hitting the target 52% of the time, but still only get a crit 2.62% of the time. What if the crit was only +15 or +10 above the target number? Let’s take a look at a sample:
attack +0 and defense 10, success 15%, crit +10 2.62%, crit +15 1.55%, crit +20 0.78%
attack +10 and defense 10, success 52%, crit +10 15%, crit +15 6.13%, crit +20 2.62%
If the bonus you have is close to the target number you’re going for, then further adjustments within ±10 will cause fairly drastic changes, but once you get outside of that range, then things change much less rapidly, though it never truly gets to a total certainty one way or the other, there’s always a chance of success or failure.
So which is the best choice for critical hits? Why, all of them and more of course! There’s no reason why there has to be only one kind of critical success (or failure) nor does every character need to share the same set of them. There are some critical effects that every character has access to, but there’s also more that an individual can get, usually from Talents. Likewise, there are some critical failures that every character can suffer, but also a character can get through Talents more critical failures that he can inflict on others who attack or in some other way oppose him.
Nor do they have to be static differences, but can change depending on the circumstances (such as by how much someone is trying to do at once). This is one of those aspects that the App will help you keep track of.
Critical effects will always be in the form of “if you succeed by X or more, then ___” or “if your opponent fails by X or more, then ___”. They should have some sort of minimum value, but I’m not sure if it should by 1, or something slightly higher like 5.
Also, for now I’m thinking that you can only apply one critical success or failure at a time.
So what’s a mitigator? It can’t be the opposite of a Critical Success, that’s a Critical Failure. But it can be the opposite of “Critical”. Criticals makes a success more successful, or a failure more failed, while mitigators make them less successful or less failed, but they’re still successes and failures.
If you’re familiar with the forums for D&D Next you might have run across whole flame wars on things such as Damage on a Miss. Mitigators are kind of like that, except not as absolute and hopefully not as divisive. They come in the form of “If your opponent succeeds by X or less, then ___” or “if you fail by X or less, then ___” so there’s always a chance for them not to trigger.
You always get access to Mitigators through Talents, there aren’t any that universally apply. Mitigators you have either apply to your own failures or to the successes of others against you (or your team).
Again, only one Mitigator will apply at a time. However, both a Mitigator and a Critical can apply at once. Say for example we have the classic double damage critical at 5 or more, and a half damage Mitigator at 5 or less, if the attacker gets exactly 5 over then they both apply and cancel each other out. Still others will have interest effects besides changing the damage amount, such as a mitigator that makes it so the attacker leaves an opening and a critical that lets the attack move to a different position adjacent to his target. Both will apply.
So what’s it all mean?
All of these together should provide a nice grade of failure to success than a simple yes, no, or double yes.
Also, for people whose skill closely matches the difficulty, small bonuses or penalties will have more significant changes for them, but less so for people who greatly outclass (or who are outclassed by) the difficulty, though in that case the chance of more powerful criticals will be affected significantly. But there’s still always a chance of that great success or great failure despite all odds.