Light That Burns the Sky compares the user's Attack and Special Attack stats, dealing damage to the target using the higher stat. If the user's Attack is greater than its Special Attack, the move will be a physical move; if its Special Attack is equal to or greater than its Attack, it will remain a special move.
During the execution of Light That Burns the Sky, all ignorable Abilities are ignored. (Ignorable Abilities are most Abilities that could potentially negatively affect the success, damage, or effects of a move if possessed by the target of a move or its allies—such as Multiscale and Friend Guard.)
For determining which stat is higher, stat stages are taken into account; however, it does not consider the effects of held items (such as a Choice Band) or Abilities (such as Huge Power) that do not use stat stages. If the user's Attack is higher, Light That Burns the Sky becomes a physical move in all aspects: the move's damage is affected by Reflect (but not Light Screen), it will activate Counter and Shell Trap (but not Mirror Coat), and it triggers the Kee Berry (but not the Maranga Berry). Otherwise, it is treated as a special move in all of these cases.
Generation VIII onward
Light That Burns the Sky cannot be selected in a battle.