Celestia is unable to stop the two evil royal sisters, Daybreaker and Nightmare Moon knocking her out before she could destroy them. However, Daybreaker is stronger than Nightmare Moon, so Luna's evil counterpart is at a large disadvantage for the first half of the battle.
Soon, though, Nightmare Moon finds a way to increase her power, and her strength becomes equal to Daybreaker’s.
As the evil sisters battle, Celestia lays unconscious on the castle floors, Luna and Starlight trying to wake her up.