In a way to personalize more our decks, i suggest the option of improving our creatures in our own way.
It means that with a considerable high cost of electrums, we could buy new abilities or strengh/defense points to our creatures. The summoning cost of the creature would increase, of course.
For example:
I want to buy 1 strengh points to my vampire so I pay with electrum coins the cost of it. Lets supose that each strengh point increase the summoning cost of the creature by 2. So now I have my new and unique vampire 5/3 that costs 7
Another example:
Now I still want to improve my new vampire 5/3 from the previous example. But now I want to give it the devour ability. Devour is a strong ability so the sumoning cost (for example) is increased by 4 and costs a lot of electrum coins. But I pay for it so now I have my extremely good but also extremely expensive vampire 5/3
:devour with a cost of 11