The showdown with Morgause was a skirmish that occurred between Morgause, Gaius, and Merlin during Arthur's Rebellion of Camelot.
Events
The battle began when Merlin attempted to destroy Morgause and Morgana's immortal army by emptying the Cup of Life. Morgause used her magic to slam Merlin into a wall, momentarily incapacitating him. Before she could finish him off, however, Gaius arrived and attacked her with a spell that threw her to the ground.
Though surprised, Morgause got to her feet and focused her attention on Gaius. In doing so, she failed to notice that Merlin had recovered from her attack and he used his magic to send her flying. Morgause was tossed into the air and cracked her head against a pillar. She was knocked unconscious and severely injured.
With Morgause defeated, Merlin quickly emptied the Cup of Life and destroyed the immortal army. This allowed Arthur to retake Camelot and forced Morgana to flee with her injured sister (The Coming of Arthur).
Trivia
- Morgause did not die as a result of her injuries, but was left disfigured and permanently disabled (The Darkest Hour).