K
Initially, the Scarlet Witch had the ability to manipulate probability via her "hexes" (often manifesting physically as "hex spheres" or "hex bolts"). These hexes are relatively short range, and are limited to her line of sight. Casting a hex requires a gesture and concentration on her part, though the gestures are largely a focus for the concentration. Early in her career, her hexes were unconscious on her part, and would be automatically triggered whenever she made a particular gesture, regardless of her intent. These hexes would only manifest "bad luck" effects. She later gained enough control over her powers that her powers only work when she wants them to, and they are not limited to negative effects. Despite this enhanced precision, her hexes are not necessarily guaranteed to work, particularly if she has been straining herself or using her powers excessively. If overextended, her hexes can backfire, causing probability to work against her wishes or to undo previous hexes.
More Info here