Donated by M Jason Parent / HellHound - this NPC uses only core 3.5 material, and is presented in the DMGII Stat Block format (although it is my first attempt with this format, so there may be formatting errors)

Isknicth _____ CR 5
Male awakened advanced dire rat rogue 3
CN Medium Magical Beast (Augmented Animal)
Init +10; Senses darkvision 60', low-light vision, scent; Listen +6, Spot +6
Languages Common, Undercommon

AC 18, touch 16, flat-footed 12 (+1 armor, +6 Dex, +1 natural)
hp 76 (9 HD [6d8 Race, 3d6 Class])
Fort +10, Ref +14, Will +6; evasion

Spd 40 ft. (8 squares), climb 20 ft.
Melee bite +13 (1d8+4 and disease)
Base Atk +6; Grp +9
Special Atks sneak attack +2d6

Abilities Str 17, Dex 22, Con 18, Int 12, Wis 10, Cha 5
SQ trapsense
Feats Alertness, Improved Initiative, Improved Natural Attack, Weapon FinesseB, Weapon Focus (bite)
Skills Climb +13, Hide +18, Listen +6, Move Silently +18, Search +9, Spot +6, Swim +15, Tumble +16
Possessions bracers of armor +1

Disease (Ex): Filth fever—bite, Fortitude DC 18, incubation period 1d3 days, damage 1d3 Dex and 1d3 Con. The save DC is Constitution-based.
Skills: Dire rats have a +8 racial bonus on Swim checks. Dire rats have a +8 racial bonus on Climb checks and can always choose to take 10 on Climb checks, even if rushed or threatened. Dire rats use their Dexterity modifier for Climb and Swim checks.