Twilight Sparkle, AKA The Masked Matterhorn, the leader of the Power Ponies. She can generate a variety of energy beams from her horn, such as energy blasts and freeze rays.

Origin:

When it's time to Power-Pony-Up, Masked Matter-Horn is at the head of the herd! Trot Summers was just a little filly when she was hoofpicked to join Professor Celestia's School for Gifted Youth. With the Professor's guidance and training, Trot is now Maretropolis's greatest defender! The Masked MatterHorn can shoot all kinds of crazy power beams from her horn, but arguably her greatest power is leadership; she pulled together the Power Ponies to put the city's most fearsome villains on ice