There is somethings I really don't like about treasure cards. :( Like when you get a really really strong treasure card you never want to use it. :( I also hate the fact that you can only use it once. I don't get it if you can only use it once what's the point? I also don't like it how some treasure cards are only treasure cards not normal spells like ninja pigs or harvest lord.
Treasure cards are meant to be one use spells that you can cast to get exposure to other schools, get around boss resistance, surprise in PVP, etc. Hence the title of Treasure Card, useful treasure using only once, if it was a multi-use then it would water down the schools uniqueness and functionality.