Like the title says, I've been playing a couple weeks and have been grinding out the daily rewards in an attempt to get more cards. Most of the time though, I get either credits or potions. The credits I see can be used in the market to buy or rent cards, but I haven't been able to find anything about the potions other than it looks like you can use them to increase the chance of something nice when opening packs. Is there any point for me as a new, f2p player to keep these? Am I able to sell them?