Talk:The Watcher in the Sky/@comment-11176760-20151115001135/@comment-26488388-20151115002317

Never, ever use metal slime unless it is for UR and above. Also, you should always use arcana when upgrading. Believe me, they seem hard to obtain at first, but you'll be overflowing with them soon (either that, or medals. I can guarantee it.)

Please see this page for reference on upgrading.