The Untold Truth Of The Scarlet Witch

In the beginning, Wanda believes herself to be a mutant, and her powers to be "hexes," which bring bad luck to her opponents. Case in point: In her first battle against the X-Men, she points to a roof above Angel, and it falls on him. 

Of course, it is later revealed that Wanda is not a mutant. Instead, the High Evolutionary experimented on her in a way that wound up making her capable of manipulating magic. Additionally, the demon Chthon accidentally gave her power over chaos magic, and she inherited her mother's own sorcerous abilities. Furthermore, she is also a Nexus Being, making her uniquely attuned to magical power. 

The upshot of all this experimentation and magical mayhem? Wanda is a tank. Manipulating chaos magic gives her the ability to warp reality. Most of the time, this is in a fairly small-scale way, like causing walls to collapse or blasting her foes with energy. However, when possessed of enough energy, she can completely remake the universe.

With regard to her witchiness, Wanda has always used traditional magic to control the elements and use various kinds of magical blasts. After that, things get nuts. Wanda has been able to heal, manipulate time, read minds, absorb massive amounts of energy, fly, and even occasionally raise the dead. For example, she brings Wonder Man back as pure energy from beyond the grave. Basically, she can do anything a story might require.