Typically, it's 50 Stones for 1 card of a selected element and 100 Stones for 3 cards of any random element. Many players will often stock up on Stones towards the end of the year for this.
==="Whale" MAX Gacha Cards===
Tucked away in the MAX Gachas, powerful "Whale" cards lurk. These cards will '''NEVER''' appear in a Special 9 Selection. <br>
Getting one of these cards is fairly random; they have a very rare chance to appear whenever you roll MAX Gachas or use an SS Gacha Ticket. <br>