Thunder Slash glitch

Thunder Slash misses.

The Thunder Slash glitch involves the skill Thunder Slash in Final Fantasy IX. Thunder Slash's base accuracy is set to 0 with a Gravity-magic-type effect and as a result, Thunder Slash is almost completely worthless. Though Final Fantasy IX has seen various re-releases, the glitch has never been fixed.

If the magic and level of Steiner (or Beatrix) are high enough compared to the target's level, the skill has a chance to hit, as the hit rate formula is Magic/4+Level-TargetLevel.

There is a second check after this for the target's magic evasion.

There have been various speculations on the bug's origin. A prevailing theory is that Thunder Slash had its Effect-code swapped with its damage-multiplier-code. The effect-code error would have caused the ability to deal fractional damage instead of weapon-based damage, but instead of using the weapon's Accuracy value, it must use the ability's own Accuracy value, which is 0%.

It is possible that Thunder Slash was not supposed to deal fractional damage (19% of the target's max HP), but rather, do x1.9 of normal damage with an added Lightning element. The value for a physical attack ability is "19", and the code for a proportional damage ability is "17". If the damage multiplier were re-swapped with the Effect-code, the multiplier would result in x1.7 of the normal damage with an added Lightning element. It is also possible that Thunder Slash was changed into a fractional damage ability intentionally, because Steiner already had a Thunder-based sword skill via Sword Magic, but the Accuracy value was mistakenly left at 0%.

Beatrix's Thunder Slash when she is fought as a boss works, dealing moderate Thunder damage to a target.