- Deals extreme damage in a threefold attack to targets behind the user.
- Family: Wyrm
- Type: Physical
- Can be dispelled: N/A
- Utsusemi/Blink absorb: 2-3 shadows
- Range: Backward arc
- Notes: Only uses this ability if the target with hate is out of reach of the wyrm's head, such as near its hind legs or directly behind it. If fafnir doesn't have enough TP, he will attack this target with normal attacks with his tail, instead. If the target still has hate when he readies a TP attack, he'll virtually always use the only TP attack solely associated with his tail, Spike Flail. Due to his high regain in combination with attacks made on him, he will likely be able to use this ability the moment a target outside the range of his head has taken hate. Damage can be reduced by Blink, Utsusemi, Stoneskin, PLD's Invincible and Sentinel. General damage is about 1600-2400.
- With the exception of Nidhogg, Tiamat, Jormungand and Vrtra Spike Flail will only hit the alliance with current hate, regardless of any outside curing. Enables many Abyssea wyrms to be 'flail-tanked' with healers outside of alliance. Azdaja being the biggest example is much easier when tanked using this method.