Every weekend a blue star labeled "Magic" will appear on you home screen and will stay there for 2 days. This particular event is called the "S-Class Mage Event". This event only appears on the weekends. A free spin is available to anyone every 12 hours after their first spin. There is also a ranking system within this event that give out additional prizes.
Not all S Class (5 Star) cards are available in this event. The only cards that are available are cards achievable in five star and six star versions. This list is as follows: Future Rogue, Franmalth, Ezel, END, Sayla, Tempesta, Kyouka, Jackal, Keith, Torafusa, Zeref, Silver, Mard, and Mavis Vermillion. Recently there has been an update that has changed this event to just the weekends. It is thought that there will be less cards for this event. It is possible the demons are no longer available and only Future Rogue, END, Zeref, Mard, and Mavis will be availble for the future. This is not confirmed yet as the update is still fairly recent.
To even make the ranking list you MUST have at least 150 points. A lot of new players will put in a few hundred diamonds not realizing they WILL NOT make the ranking list. To get 150 points you must have at LEAST 5,400 diamonds. However to actually get first place in ranking, typically you will need much more than 150 points. Every 5 points costs 180 diamonds (excluding any free spins you will get.) The amount of points needed to win first prize can vary greatly depending on who is competing within that particular server.
No matter what card is available, the amount of cards or prizes you earn per rank will stay the same. First place will always receive three of the card in question as well as one additional fetter card. Second place receives two of the card as well as the additional fetter. Third place receives the card and the fetter card. Fourth place receives the card and 1 million gold. Fifth place receives the card and 950 thousand gold. Sixth place receives the card and 900 thousand gold.
There are different points intervals that can achieve additional bonuses.
There are additional prizes won on each spin.
Winning the Free Card
Once in a blue moon you might get lucky and get a free card. Tell your guildmates! Depending on who you got they could hate you for forever. Use it to your advantage as much as possible. Gloat like crazy.