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
Won't happen. Because people would make multiple accounts, use the first login bonus to buy packs and then trade all the good cards. They would have to remove free gems in the game and that would discourage new players from joining