Final Fantasy XIII
Lightning, the main protagonist in Final Fantasy XIII, has an affinity with Gravity. This allows her to perform moves that completely defy the laws of physics and the Gravity Bomb seems especially potent.
As seen in a trailer for the game, when the move is performed Lightning throws a bomb at the ground which explodes and it causes the area surrounding her to effectively become "anti-gravity". This causes any foes in the surrounding area to be sent flying into the air, unable to move of their own free will.
Jumping From Great Heights
Lightning is also able to use this ability to jump from great heights. This is seen during the opening sequence of Final Fantasy XIII, when she leaps off a tall structure and lands effortlessly.
Sazh Katzroy then jumps after, having a much less graceful landing. It's inclear whether this therefore means the gravity bomb has a specific time frame, or Lightning decides when it works.