Gravira

Gravira (グラビラ, ), also known as Demi 2, is a stronger form of the spell Gravity in the Compilation of Final Fantasy VII. As a gravity spell, it does damage to the target based on a percentage of its HP.

Final Fantasy VII
Demi2 reduces one target's health to 1/2 of their current HP for 16 MP and is the second level spell on the Gravity Magic Materia.

Before Crisis -Final Fantasy VII-
Gravira costs 50 MP to cast and does moderate Gravity-elemental damage to enemies.

Crisis Core -Final Fantasy VII-
Gravira is an ability exclusive to Movers. As with most Gravity spells it does damage based on Zack's current HP.