Cristiano Crystal Shoot! (X-BT01/0048EN) (X-BT01)

This card can only be used during your opponent's final phase if you have not been dealt any damage this turn, you have a size 3 "Prism Dragon" on your center and your opponent has 4 life or less.
[Cast Cost] [Pay 2 gauge]
[Counter] Deal 4 damage to the opponent! This card cannot be nullified and the damage cannot be reduced. If your opponent's life becomes 0, your opponent cannot change his or her life by cards (cannot revive).