Upon capturing all the Clow Cards and slowly transforming each one into Sakura Cards, Kinomoto Sakura faced her final judgement against Eriol. Much like Clow's magic, Sakura's magic is a balance between the sun and moon, which is later noted by Clow himself, stating Sakura's magic comes from a brilliant, ever-shining star.
Because she successfully transformed all the cards and developed her magic steadily, Sakura is said to have surpassed Clow Reed as being the most powerful magician in the world.
Cute cosplay. I wonder which card she's holding? Perhaps Windy, her favorite card, or the Hope Card, the last card which is also known as the unsealed card. Guess we'll never know unless this cosplayer herself tells us. Great work!