Heaven's Cataract is a Blue Bullet spell, learned from the Chac, Gucumatz, and Kukulcan enemies. It deals non-elemental magic damage to all enemies, and reduces their Defense and Magic Defense by two levels for the MP cost of 22.
Heaven is a common religious, cosmological, or transcendent place where heavenly beings such as gods, angels, jinn, saints, or venerated ancestors are said to originate, be enthroned, or to live. According to the beliefs of some religions, heavenly beings can descend to earth or incarnate, and earthly beings can ascend to Heaven in the afterlife, or in exceptional cases enter Heaven alive.
震天 "Shinten" is a Chinese verb that literary translates to "(something so forceful that it) shakes the heavens".