Complex sentence: Casting a hex requires a gesture and concentration on her part, though the gestures are largely a focus for the concentration and, despite this precision, the hexes are not necessarily guaranteed to work, particularly if Wanda is tired or using her powers excessively.
Split into simpler sentences: Casting a hex requires a gesture and concentration on her part, though the gestures are largely a focus for the concentration. Despite this precision, the hexes are not necessarily guaranteed to work, particularly if Wanda is tired or using her powers excessively.