Gravity Seed is a powerful sorcery spell that has been primarily employed by Nine the Phantom.
Information
The spell greatly increases gravity in a certain area, making it near impossible for its victims to move as they are pinned to the ground. Nine first demonstrated this spell as Phantom, where, under Izanami's orders, she used it to pin Rachel Alucard, Nago, and Gii in the charred remains of Celica A. Mercury's Church.[1]
This spell was used again by Nine under Izanami's orders to pin Hibiki Kohaku, Jin Kisaragi, and Kagura Mutsuki.[2] The power of this spell is so great that the three of them struggled to move from underneath it.
Both Lambda-11 and Nu-13 have moves in their command lists named Gravity Seed that function similar to this spell, but they are not the same thing. Nine has a move that also functions identically to this spell called Celestite of the Covenant.