I recently bought some Spell cards, as you do. For some reason they are now gone from my decks. I emptied out every card from every deck to make sure they were gone. But, YES, GONE! Are spell cards that you buy, a one time use ? Was/is there a box to check to keep said cards? This is not the first time this has happened. I thought I did something wrong then. Now its happened again and I'm not impressed. I don't remember the names, but.... The sand whirlwind The big fat frog The shark The fire balls I HAD over 20 Treasure (different) cards. There was others but I don't remember. I have bought 500 Shield again, but shill only have 1, will it too disappear? Also just bought Poison (Death) and Skeletal Pirate, will they disappear too?
Treasure Cards (Gold Border) are one time use. You can get them by buying them from Libraries (Wizard City for example) as well as the Bazaar. You also get them from defeating monsters and completing quests as well as Gardening.
If you train the spell with a Training Point from the Professors at Ravenwood these spells do not disappear and can be added to your spell deck.