demiurge1138 said:
Severing Bite: He ate the hand of a god, after all. He's epic--let's make those high level PCs use their regenerate spells the way they were intended!
Amen to that!
I'm on-board with everything else you posted.
Brachyurus scores: Str 30, Dex 38, Con 47, Int 18, Wis 32, Cha 19
Since the Fenris Wolf is 50-freaking-feet-tall, I'd say he's Colossal.
Boosting those scores to Colossal yields: Str 54, Dex 36, Con 59, Int 18, Wis 32, Cha 19
Brach's claws deal 2d6, bite 3d6. Bumping to Colossal goes to claws 5d6, bite 6d6.
Even with 54 Str, the bite still is only doing 30-60 points of damage. That's still 30 points shy of the 90 it could do on the high end.
How about combining severing bite with augmented critical to this:
Augmented Critical (Ex): The Fenris wolf's bite threatens a critical hit on a natural attack roll of 18–20, dealing triple damage on a successful critical hit. Additionally, the victim must succeed on a DC X Fort(?) save or lose a hand or foot (Fenris wolf's choice?) (Go on to describe what happens when missing said appendages).