Board Thread:Game Discussion/@comment-13765649-20140730180829/@comment-72.77.162.74-20140730192012

There is none. Bust your ass on day 1 of a raid event and you should be able to get a lot of medals. Use those to either upgrade your R6 or save them to upgrade raid cards. In campaign events there is usually a low level (such as Easy 1-1) that will give 10 transmetal units for capture. Farm that for as much as possible. R6's are very hard to upgrade. It can take a few events before you get enough to do it.