Talk:Argon Crystal/@comment-86.128.203.50-20150128205408

Heh, these are actually rather easy to farm, I tend to go with Mobile Defense since the enemies won't scale the longer it goes on. Plus it has a relatively non-liner map most of the time.

Strange, when I was new it seemed so difficult, now that I'm almost rank 9 (under 2,000 more from the challenge) it seems easy to get.