The best place that I found to grind for coins in world 2 is in the castle in the top right area of the map. Go in, take the right entrance, then go through the north door of that room, then through the door to the right. There should be 12 vases to break there. If you walk in between the tiny crevice between two pots you can smash 2 at once, allowing you to clear the place and pick up drops twice as fast. In addition, there is a pig solder on the other side of the wall that you can sometimes hit with your blue boomeraxe if you have it for a bit of extra exp. I was able to get the 15000 coins needed for the armor at the store after about 3 hours of grinding, which was boring, but was somewhat worth it.
for the last mission, have a lot of contamination cards and not much else. put in a few life draining cards and some creatures. keep up a defensive wall of creatures and store up black energy for contaminations. when the opponent is low on health, use the life drains. dont attack with your actual creatures, use them to block.
this works best if you only have like 30-40 cards in your deck.
Complete Card Conquest
Dude! You just completed the Complete Card Conquest achievement in Mytheria and won the Complete Card Conquest badge and 15 points!