The captive rancor has a soak of 12. Is this going to be a canyon krayt or greater krayt? If a canyon krayt I would put the soak at at least 15 (probably 20 or so for a greater). Silhouette 3 for canyon krayt (a greater could be sil 4). And a rancor does 15 damage on a hit. Would not a larger krayt do more?
How about this?
Canyon Krayt Dragon (Nemesis)
Brawn 6 Agility 2 Intellect 1 Cunning 2 Willpower 3 Presence 1
Soak Value 15 Wound Threshold 60 Strain Threshold 20 M/R Defense 1/1
Skills: Brawl 2, Survival 2, Vigilance 1
Talents: None
Abilities: Silhouette 3, Massive 1, Adversary 2, Tail Sweep (Can spend a Triumph on a successful Brawl attack to knockdown another target engaged or at short range from the dragon).
Equipment: Vicious bite (Brawl; Damage 20: Critical 2; Range [short]; Ensnare 1, Inaccurate 1, Knockdown, Pierce 4)