In the co-op game The Big Book of Madness, the rules say the following about when you acquire a new Element card:
As long as one is available, you can acquire 1 Element card of value 2 or 3 from the middle of the table. You must spend Elements of the same type as the Element card you wish to acquire. [...] When you acquire an Element card, place it in your discard.
So you spend several Element cards to acquire a new Element card of the same combined value. The new card goes in your discard.
Do you destroy the spent Element cards or do they go in your discard as well?