Choose what the dragon keeps.
When an order wants a prism, choose whether to fill it or grow your dragon's collection. You have 6 seconds. If you wait, it goes to your bag when wanted and there is room; otherwise the dragon keeps it. Unwanted prisms go straight to the hoard.
A Heartstone takes three pries. In Career it gives the dragon 12 hoard. In Free and Daily, choose 600 coins or 12 hoard; waiting sells it.