Critical threat range miscalculation

[ihillway]

We are currently playing through a pathfinder campaign (I believe it is called "Eyes of the Ten") and

Spoiler:

we came across a fighter with a critical threat range of 15-20 with a longsword.

Normal critical threat range with a longsword would be 19-20, if you double it due to keen or improved critical (rules say that they do not stack) then it improves to 17-20, yet somehow the crit range is tripled... to 15-20.

How can this be? It seems like this violates the rules. Is there just an error with this NPC in this module or is there a rule I am missing?

Here is his stat block...

Teko CR 14
Male human fighter 15
LN Medium humanoid (human)
Init +1; Senses Perception +0
Defense
AC 29, touch 14, flat-footed 27 (+11 armor, +2 deflection, +1 Dex,
+1 dodge, +1 natural, +3 shield)
hp 157 (15d10+75)
Fort +13, Ref +7, Will +6; +4 vs. fear
Offense
Speed 30 ft.
Melee +2 keen longsword +26/+21/+16 (1d8+11/15–20)
Statistics
Str 18, Dex 13, Con 16, Int 12, Wis 10, Cha 8
Base Atk +15; CMB +19; CMD 33
Feats
Bleeding Critical, Cleave, Critical Focus, Critical
Mastery, Dodge, Exhausting Critical, Greater Weapon
Focus (longsword), Improved Bull Rush, Improved Critical
(longsword), Power Attack, Sickening Critical, Staggering
Critical, Tiring Critical, Toughness, Vital Strike, Weapon Focus
(longsword), Weapon Specialization (longsword)
Skills
Climb +20, Intimidate +17, Ride +17, Survival +18
Languages Common, Goblin
SQ armor training +4, bravery +4, weapon training (heavy blades +3,
light blades +2, bows +1)
Gear
+2 full plate armor, +1 heavy steel shield, ring of protection
+2, amulet of natural armor +1, cloak of resistance +1, +2 keen
longsword

[Eryx_UK]

Maybe they are forgetting that keen and imp critical don't stack?

[Xaratherus]

Eryx_UK is most likely right: They are stacking Keen and Improved Critical, and those explicitly state that they don't stack.

[ihillway]

That was my initial thought, but seeing something like that in an official pathfinder society module... well I didn't want to just assume that I wasn't just ignorant of some rule.

[Xaratherus]

It wouldn't be the first time a mistake was made. Paizo's designers and authors aren't perfect. :)

[Michael Sayre]

I believe that's a pretty old scenario too (at least 3 or 4 years), maybe even Season 0, so it's possible that it was written at a time when they were considering having those abilities stack.