Master of Games

The Master of Games is the main villain in the Teen Titans episode "Winner Take All".

He transported Robin, Cyborg, and Beast Boy to his colliseum. Anyone who loses the match gets aborbed by the Master Of Games's red gem and steals their powers

However, Robin fought the Master Of Games and freed Cyborg and another hero named Speedy from the red gem. Then, Robin defeated the Master Of Games and freed the other heroes (including Beast Boy) from the red gem. Then the Master Of Games disappeared.