Turns in a circle, striking with backhand blows to attack adjacent units.
The Ivalice Chronicles' description
Cyclone, also known as Spin Fist, is a Martial Arts ability in Final Fantasy Tactics, learned by the monk job. It is a melee attack that deals physical damage surrounding the user. The action ability must be learned by expending JP earned for the monk job.
Obtained
Cyclone costs 300 JP to be spent on the monk job. Once the unit has learned it, it is available for other jobs as long as they have the Martial Arts skillset equipped.
If a unit that knows Cyclone becomes a crystal, a human unit picking up the crystal may learn Cyclone without spending JP, as long as said unit has unlocked the monk job.
Mechanics
As a basic Martial Arts ability, the damage it deals is calculated as follows:
The success rate formula is:
Cyclone attacks all tiles surrounding the user that are of same elevation. It has no MP cost.
Use
Cyclone attacks all units around the user that are on the same elevation as the user, dealing damage based on the users' physical stats. If the unit is surrounded only by enemies, it can be a good alternative to using a normal attack as it will hit multiple targets at once. Against a single target, the damage will likely be lower than a normal attack, and the ability does not have a 100% success rate, meaning it should only be used defensively.
Cyclone is an inexpensive ability to learn, and Martial Arts comes with several abilities that multiple jobs can benefit from (such as Aurablast, Shockwave, Chakra, and Revive). However, compared to other learned monk abilities (such as the aforementioned Martial Arts, or Counter and First Strike among other abilities learned from monks), it is a lower priority to learn.
Etymology
In meteorology, a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth.