Success, Failure and the D20

[Gronin]

PCs should succeed 78% of the time.

That is, approximately 78% of all attacks should hit. They should win roughly 78% of all battles *. They should succeed on roughly 78% of all Skill Challenges (and, when faced with a single skill check, they should succeed... 78% of the time). And so on.

* Note: the choices here aren't "win" or "TPK". There are the stalemates, the tactical withdrawals, those encounters where they're clearly overmatched but..., and of course encounters where they're just unlucky!

I'm curious where the 78% percent comes from as opposed to say 75% or 80%?

 

[Gronin]

I would think that if you are competing against someone or something of equal ability then there should be approximately a 50% chance of success or somewhere in the 9 - 12 on a d20 range.

Keep in mind this should be strongest attack against strongest defence and vice versa. Obviously if you find a way to use your strongest attack against your opponents weakest defense this should result in a better than even chance of success.

 

[Crazy Jerome]

I think it has been reasonably well shown (though not proven) that players feel satisfied when they succeed somewhere between 2/3 and 3/4 of the time. Slightly less than that is fine for tough things, and slightly more than that is fine for easy things.

The problem, of course, is that "succeed" is still a fairly rickety concept. If you roll a 19, roll lousy damage, and the monster immediately saves on a status effect before it can accomplish much, did you succeed or not?

 

[delericho]

I'm curious where the 78% percent comes from as opposed to say 75% or 80%?

Well, to be fair, I pulled it out of the air.

However, the guys at WoW have done significant analysis as to where the "sweet spot" for success is. The survey was quoted here just before 4e hit (IIRC), and I believe the value they were quoting was between 75% and 80%.

 

[babinro]

I think a natural 8 is a comfortable zone to hit standard monsters with others ranging from 10 to 12 being the most extreme before bonuses like combat advantage.

I feel the math in 4e has major problems and that the Expertise feet are needed. Expertise fixes the math problems a lot for hard to hit creatures as certain levels, but at the same time makes other monsters a joke.

Level 30 is an example where Expertise feats are really needed in 4e to counter the OP's example. End game monsters tend to have around AC 48-51. The typical character will have Attack vs AC of +35/+36 depending on weapon choice with expertise feat. Thanks to the math fix, this means the PC can hit on a 12-14 natural roll. Without it, PC's hit on 15-17...something nearly all players would find boring or potentially unfair.

The problem here doesn't have an easy fix though as it would involve the errata of too many monsters at too many levels. When I DM, I simple make the changes necessary to keep the battle interesting.

 

[Gondsman]

Why does this feel like a DM vs Powergamer Ragging Session? Not to insult anybody now, it's just that i've always approached things from the perspective of good old rule-0. If the PC's are hitting too often, I've dropped the ball as the DM. Keep in mind you can throw a fellow with a boosted AC at them, and the other characters are gonna have more FRW attacks that will let them hit with lower bonuses.

My opinion....I think that sometimes the PC's should get chances to hit most of the time, and other chances to struggle for every hit. Anybody who follows Chris Perkins' columns knows that variety is the spice of life for PC's. Even the Munchkin, Min-Max, Power Gamer won't stay interested for long unless he encounters challenges that prove the value of his play style. If he always hits, and kills everything he looks at, he's just gonna move on to the next build. It's all about Highs and Lows.

 

[AbdulAlhazred]

Yes, but you will only fight one demonlord/god/primordial/great old one/whatever one time (for keeps) in a whole campaign. You don't HAVE to be able to hit such an extreme creature on a 12. In fact the whole point of such an encounter should be that the PCs cannot win without perfect tactics and probably some kind of systematic story-related advantage. If Demogorgon fell to every 30th level party he'd have been offed LONG ago. You gotta first forge the one weapon that will whack him reliably, and attack him at the Grand Conjunction after carrying out the Ritual of Ultimate Purification. THEN you can hit him on an 8...

 

[Vael]

I play an Elf Scout in Encounters, so that I know that in order for that human to get a +10 he must've optimized for a 20 DEX (which, since he only gets one stat boost, means he's gonna have crappy FORT and WILL), took the option for wielding a light blade in the off-hand to get a +1 to attacks, be using a Longsword or Rapier in the main hand to get +3 proficiency bonus, and took Expertise of some kind. That means he's investing A LOT of resources to get that +10.

He wields a Spiked Chain (yes, I know it's not Encounters legal, but we stopped restricting character generation during March of the Phantom Brigade, keeps the regulars happy), and has Light Blade Expertise, and yes, that is where all his resources went. That definitely bit him this week when he noticed that two bandits were still up, he had few hitpoints (my dice were pretty hot), and the rest of the party was down. No training in heal, and his 14 went to CON meant he actually fled the battle. Only a nat 20 death save from the Knight saved the party.

 

[UngeheuerLich]

10 should be ok on average... but encounter and dailies need to be reliable or have miss effects... otherwise it may get too swingy...

i like power attack style powers.

 

[delericho]

Yes, but you will only fight one demonlord/god/primordial/great old one/whatever one time (for keeps) in a whole campaign. You don't HAVE to be able to hit such an extreme creature on a 12. In fact the whole point of such an encounter should be that the PCs cannot win without perfect tactics and probably some kind of systematic story-related advantage. If Demogorgon fell to every 30th level party he'd have been offed LONG ago. You gotta first forge the one weapon that will whack him reliably, and attack him at the Grand Conjunction after carrying out the Ritual of Ultimate Purification. THEN you can hit him on an 8...

I can't give you XP, so I'll just say: I agree with everything you've said here.