Best grind map is the one with huge bomb, it should give you about 70k gold everytime. You just keep grinding it until everything in your army is lvl 5 and then start doing it in epic and get something like 200k every time, but in epic you need to learn to dodge the explosion of the bomb.
Seriously the most annoying shit ever! Im 30 meters from getting card and my stupid character cant jump anymore for some reason and once again walks in to the pit.
Goggi2005 if you are having a match against someone like that its auto win for you because he doesnt do anything. after few turns there should be a grey box or something with 1 min time. after the time has passed you can claim victory.
I actually won a card that way from unranked match even though its only 1% chance.