OK, I'm updating the serpentfolk from Into the Darklands to PFRPG. I am working up the 'degenerate' version of the serpentfolks and so far here's what I have.
Degenerate Serpentfolk CR4
NE Medium monstrous humanoid
Init +1; Senses Darkvision 60 ft., scent; Perception +10
Defense
AC 18, touch 17, flat-footed 17 (+1 Dex, +7 natural)
hp 47 (5d10+20)
Fort +9, Ref +8, Will +8
Immune mind-affecting magic, paralysis, poison; SR 15
Offense
Speed 30 ft.
Melee spear +10 (1d8+7, x3) and bite +8 (1d6+2 plus poison)
Statistics
Str 20, Dex 13, Con 19, Int 4, Wis 13, Cha 6
Base Atk +5; CMB +10; CMD 21
Feats Great Fortitude, Multiattack, ??
Skills Perception +10, Stealth +6
Languages Aklo
Special Abilities
Poison (Ex) Bite - injury, save Fort DC 20, frequency 1/round for 6 rounds; effect 1d2 Str; cure 1 save.
Does this look right? Man, it's pretty buff. I'm taking the ability scores from the 3.5 version, and the degenerates there have +4 poison save DC, +4 Perception (well, Spot, but whatever). They get upgraded with more feats, skills, hit points, etc. per the PFRPG monstrous humanoid changes. They're huge combat monsters and the immunities and poison make them really hell on wheels.
I chose Stealth as an additional skill because it seems like they skulk around underground a lot and otherwise they'd have like +13 Perception.
It needs one more feat. I thought about Power Attack but damn... Using a spear two-handed, as is their wont, that makes them spear +8 (1d8+13, x3) and bite +6 (1d6+6 plus poison) - that's a lot of frickin' damage. Toughness maybe, not that they're short on hit points either? Well, and the monster stats by CR table says 16 average damage for a CR4's main attack and 12 for a secondary is good... Without PA it's only 11.5 (with it's 17.5). So I guess Power Attack it is. Thoughts?
[Edit: Oh wait that's supposed to be for all their attacks together... These guys either need their stats nerfed hard or need to be higher CR I think. The superstats and SR make them tough; I think one would totally rape a CR4 minotaur for example.]