Not easy to activate since you have to have a level 6 monster, but special summoning Dark Magician from your deck without cost is useful. You may want to use if your deck is based on Dark Magician/Dark Magician Girl and cards which support those two monsters.
This drop rate is horrible. I have beaten her with a duel assessment of 5000+ over 40 times and I cannot get this card. Only card I need to complete my dark magician deck. I should've chose sages stone with my reward for kaiba corp. I can't wait till next tournament. I'm not gonna get this card unless I save 1000 keys and I that might not even get me it lol