Scalding tarn is only going to be involved in a trade with misty rainforest.
Other notable cards I have for trade
Shocks
Foil mma knight of the reliquary
doubling seasons
engineered explosives
Bonfire

lots more in my trade list. If trading for two mistys I have at least one of every shock even if its not in my trade list. Could be taken out of one of my various edh decks. Need 2 mistys 4 hierarchs