Mijin Gakure
From Final Fantasy Wiki
Mijin Gakure is a Ninja ability in Final Fantasy XI. It is their two-hour ability and it is available to all ninja level 1 and up. Mijin Gakure is completely different from any other two-hour ability since its effects are instantaneous, like Benediction, but it will actually kill the ninja when it is used. The ninja will explode, quite literally, in a burst of flame and deal damage to a creature. The amount of damage is directly related to the amount of HPs the ninja has remaining, so if the ninja is low on HPs it will have little effect. The one advantage to this is there is no XP loss for this kind of death and it could potentially do quite a bit of damage so the death of the ninja might actually save the party.
