D&D 4E What's the assumed average chance for a monster to hit a PC?

[Sword of Spirit]

I'm working on reverse engineering the actual rules of monster creation in 5e, and I realized that 4e math could really help me out, because it was based on research, and the 5e designers took note of that. For example, the assumed chance of a PC to hit a monster in 5e is assumed to be 65%, which I believe is math that debuted in 4e, which in turn probably was put in because psychological studies indicate that a 2/3rds chance of success is most satisfying in this sort of thing.

What I do not know, and am hoping some of you who are better versed in 4e design and theory can help with, is:

What is the assumed average chance of a monster hitting a PC in 4e D&D?

And of course, these are massive generalizations, but they are generalizations that are baked into the math of both games, so there is an answer.

 

[b_took]

Monster attacks are (originally; I can't recall if MM3 changed anything in this regard) Level+5 vs AC and Level+3 vs NADs per the DMG.

Minimum AC for heavy armor is 6, so the average monster will hit on a 10. Go up to plate and a heavy shield, and the average monster will hit on a 14.

The game was built assuming 16 in relevant stats (PHB Standard Array is 16,14,13,12,11,10), so attacks vs NADS also will average out to hit on a 10 once class/race bonuses to NADs are considered.

A little better than a coin flip was the goal.

 

[Joshua Randall]

This is the seminal article on this topic from the PC side

Calculating hit chances using attack and defense normalization.

D&D 4E' s combat rules are set up so that attack and defense values of both player characters and monsters increase at a regular rate of 1 p...

squarefireballs.blogspot.com

Not as much work was ever done from the monster side but b_took has the gist of it.

 

[Sword of Spirit]

Thanks to both of you; that's quite helpful!

Is there a version of that link that still has the graphs?

 

[Tigris]

Some comments:

- In 4th edition it was easy/common to got combat advantage, which got a +2 to attacks, which got you to the 65% (base hit on 10 is 55%)

- Monster manual 3 did not change hit chance it stayed like this

- 5E does assume for balancing having NO magical items. It only assumes proficiency and stat increase. (Not sure why, but in 4E items and all was included in balance for players)

- 5E has a really strange power scaling (trippling from 1 to 3, doubling from 3 to 5, then doubling from 5 to 9 or so), where 4E had a constant one look at the links in the scaling section:
- I know that the 5E monster rules where different (using level like 4e not CR) in the last playtest, but where on short notice changed.

 

[Joshua Randall]

Is there a version of that link that still has the graphs?

Sadly that page of Square Fireballs was not crawled until 2023 (?!) but you could mostly re-derive the charts based on the formulas and explanation towards the bottom fo the article.