Knowledge Skills in Combat

[billd91]

It doesn't invalidate the approach/rule if there are exceptional cases where it doesn't work as well as in the majority of cases. A rule that works in 90% of the cases is still better than not having any rule at all, but maybe that's just my opinion.

My assertion is that the rule takes the wrong approach entirely and, if there are any DCs that work reasonably well, they are serendipitous rather than appropriate by design.

I think the DCs that tend to work out OK work out because frequency, in many cases, correlates with CR. Weak monsters are more common than strong ones in general. But because of the design, a relatively common strong monster is harder to know anything about than an extremely rare weak one.

In addition, because the CR is determined by looking at HD + special abilities, the knowledge threshold for creatures with a lot of special abilities becomes very high. So not only are there generally a lot of special abilities, the more obscure of which require even higher DCs, but you're not even going to know the most frequently used ones without a huge investment in skill ranks. I'm content with more obscure abilities requiring a higher DC than the base one, I just think the base ones, if based on CR, tend to be inappropriate.