For everyone who can't get that first battle to work because you need 50+ soldiers and two frontline units - click on Soldiers TWICE so that two green ticks appear. Yeah, it would have been nice if it told you to do that...
I'm surprised no-one has mentioned selling potions! Keep your stock at about 5 or 6. You'll have plenty for healing if you need it, but it means you can pick up extras when they appear and sell them. Earns thousands that could be lost early on by staying too well equipped.
I can't help feeling that the Epic War series has lost more features than it's gained. I can no longer see a mini map, I can't select individual units to see their remaining health, the graphics have gone quite cartoony which looks a lot less 'epic'. I'm struggling to see what features have been added to make the game better than, say, Epic War III.
Apparently you can do low level battles without a full deck, but without my useful spell card (which has now completely disappeared from deck along with the duplicates) I don't have a deck that can win even the early battles.
Removing cards from your deck that are duplicates seems to remove them completely. It's now impossible for me to have a deck with more than one gold mine, peasant, etc. Also cannot make a full deck, and therefore cannot battle to gain more gold to buy new cards. Utterly stuck.
By the way, those finding the keyboard controls might want to try this setup:
Put your right hand sideways on to the keyboard:
Thumb: Space bar
Index: V
Middle: G
Fourth: Y
Little: 7
Then just play it like a piano!
Mirror it for left-handers (Space, B, G, T, 5).