(note that I posted this same message in general under the topic ‘Curent and future state of the game discussion’)
The game has 2 kinds of currency, runes 
and crystals 
. Runes should only be associated with ‘playing the game’ stuff (like planeswalker experience and health regeneration 
) and crystals are for buying new cards 
.
To address the health question, simply allow healing potions
to be purchased with runes
.
As for converting duplicate cards into runes, they should instead be converted into crystals
since all you can do with them is buy more cards. My suggested trade in rate for dupes in crystals are; commons=2, uncommons=3, rare=12, mythic=60.
However the issue of getting those last few cards in a set is still an issue.
I suggest that making a new kind of pack that GUARANTEES at least 1 non-duplicate per per pack
.
To prevent people from only buying those packs, or making them wayyy to expensive, how about making a new kind of currency - say crystal dust or gems 
, and you can only buy those special packs with the new currency.
The only way to get this new money
would be by converting duplicate cards into it…AND the new packs
can be unlocked to be purchased with regular crystals
when a players collection reaches 70% of cards in that set. After that point its diminishing returns on your chances to get a new card in a pack, so with these new packs unlocked at that point both players and developers are satisfied. It also quells the pack percentages issue since there is a solution to getting your missing cards once you have a critical mass of cards in a set. Maybe even give the ability to upgrade regular packs to special ones at a cost.
I hope with the expansion that there are many new objectives in story mode, and since you get runes for playing any match, all secondary objectives should be in crystals.
I also wanted to mention that I am very impressed with the rebalancing of the planeswalkers so all abilities cost the same and increase in power as you level. That is a very good solution to getting people to level up. I do think that the 9 cost first rank abilities could be reduced by 1 or 2, however with going to level 60 and adding a 4th rank, we shall see what interactions with planeswalker points are introduced, such as bonuses and cards that interact with them. I would really like some feedback on the ideas I suggested above.
