Quaga is a magic spell in Final Fantasy VII Rebirth. It is granted by either 
Petrify Materia or Poison and Petrify Materia. It is the strongest petrifying spell above 
Quake and Quakera. Quaga inflicts large non-elemental damage, as well as inflicting the 
Petrify status to one enemy.
Use[]
Quaga can be cast when either petrify or poison and petrify materia is equipped. The spell deals very strong non-elemental damage to a foe, although it comes with a high MP cost. It also inflicts the petrify status, a very dangerous status to a foe that causes them to turn to stone if they receive enough damage during the status.
Quaga's non-elemental damage is among the strongest of any spell. It is greater than Bioga, and though it is below that of Comet and Cometeor, it is more reliable and has a much shorter cast time. Quaga therefore is a very strong way to deal magic damage generally to an opponent, but it is less efficient than targeting an opponents' elemental weakness if one is available.
Quaga can benefit greatly from 
Support Materia. Both HP Absorption Materia and MP Absorption Materia can increase a party member's sustainability when using the spell. Magic Focus Materia can increase the spell's damage, and Magnify Materia can make for a powerful combination when it hits all enemies at once. Magic Efficiency Materia can alleviate its high MP cost, and Swiftcast Materia can reduce its cast time.
Using Quaga with Aerith's Arcane Ward will cast it twice. Further using Yuffie with Doppelganger when in Arcane Ward can cast Quaga four times, potentially overwhelming enemies.
Quake cast with magnify and magic focus can be good against the large group of tonberries faced during the "Can't Stop, Won't Stop" quest at the Musclehead Colosseum.