Board Thread:Dark Souls/@comment-211.30.219.116-20140903113836/@comment-5264386-20140903123814

A while back, I wondered if there was a way to estimate the defence values for AotA enemies, since their stats are obviously not in the official guide. Thus, I went searching for formulae, and I did find a set of them. They showed that, as you've already seen, the function of AR vs Dam vs Def is a hybrid function of several components; however, I suspect the formulas I found (source) vary somewhat from your results:
 * 1) When AR < defence value, Damage = 0.4*(AR^3/ Def^2) - 0.09*(AR^2/ Def)+0.1*Atk.
 * 2) When AR = defence value, Damage = 0.4*AR
 * 3) When AR > defence value, Damage = AR - 0.79* Def*e^(-0.27* Def/AR).

However, there are anomalies within these estimated functions. For instance, when I was testing the combination of ARs necessary to produce the Firelink Shrine Hollows' average defence value (which is what I suspect the official stats are), a Butcher's Knife +11 produced a much lower defence value than that of the weapons both immediately prior and after it. This result has been replicated during my testing on Bloatheads and their Sorcerer counterparts. Furthermore, I found that a Greataxe class weapon will do far more damage to the Chained Prisoner miniboss than any other weapon, for no other reason than "for the lulz".

Regardless of the above, kudos for taking the effort to actually determine the formula. It's a shame that there's not really a more efficient way of testing enemy defences, though - save getting more people on board, of course.

Anyway, if you're interested in looking at my (very limited) results so far with calculating the defence values of AotA enemies, you can check them out here.