Oathbreaker opens up the possibility of making some current cheap cards jump in price. There’s always been a market for foil Planeswalkers, but they could become even more popular now. Here’s looking at you Tibalt, the Fiend-Blooded”
The Signature Spell slot could greatly increase the demand of certain foil instants and sorceries. Which ones do you believe are going to see a jump in price? Which ones are you buying up now? Hoard them, my Dragons!