Board Thread:Questions and Answers/@comment-106.137.78.29-20150522051157/@comment-26044227-20150522054609

I'd recommend 30+ for World 4. It depends on how much you care about losing troops constantly, but I'm an impatient person, so if it's just one low-level sword you need to train, I'd set them as your leader, give them some shields, and just grind through some higher level maps so they catch up more quickly. If there are several low-level swords to train, it might be better to take them onto lower maps first.