Kingdom Hearts Re:Chain of Memories

For this trophy you must turn 20 cards into Premium Cards; when a card becomes Premium the CP required to have it in your deck is lower, however it will become an unreloadable card. To change cards into Premium Cards you must pick up the Premium Bonus ( which initiates a pinning roulette with your deck where you can select one to become a premium card or back out.

Premium Bonuses are rarely dropped in normal battles however have a higher chance of dropping in White and Black Room Map Cards. There is even a Map Card specifically for it called Premium Room which guarantees more frequent Premium Bonus chances. After you have turned your 20th card into a Premium card your trophy will unlock.