Wagic is an heroic-fantasy game in which you battle as a sorcerer against your PSP. It is based on the rules of a very famous collectible card game. In Wagic, you create a deck of creatures and spell cards, then play with this deck against the AI
I don't have a wii u anymore to test it myself, but if homebrews are not visible on the wii u menu I think you can press L + R + minus to open the plugin menu, there should be an option called "homebrews on wii u menu" or something similar
Or when your player dies, you can say in code, if enemy exists, do nothing, but if enemy does not exist, then create enemy at certain spot. (This would be a pain tho for lots of emeies)