Normal: "A fiend that attacks with alarming speed despite its otherwise lethargic movement. Its icy breath can damage multiple targets at once. Chilling." Oversoul: "Carries a grudge against gun-wielding opponents. It attacks them with great persistence, but its reasons for doing so are unclear." — Scan
They are moderately more difficult than the Bolt and Lesser Drake, though not terribly difficult aside from when it Oversouls, at which point it is best to not use Gunner, Gun Mage, or Alchemistdresspheres to avoid too much damage. It is also advisable to use Ice-resistant equipment and abilities to avoid damage from its Breath attack, or use Shell.
In the Fiend Tale endings, a notable Spine Drake lived in an area where his kind were at odds with the Drakes. But when both types join forces when their children run off, Spine Drake reconsiders his prejudice and is selected to represent the Drakes at attended at a peace conference between his kind and the Ruminants represented by Balivarha. However, it turned out to be a trap by Yevon monks to pit the two fiend types against each other. Luckily, Divebeak, Vertigo, and Barbuta revealed the treachery and Spine Drake joins forces with Balivarha against their common enemy.