User blog comment:Secondshadow/Type-Based Teams: A Bad Or Good Idea?/@comment-26297531-20150820012901/@comment-26865510-20150820022601

Exactly, which makes this approach more of a passive and nuanced strategy than an active one. For instance, I don't recommend that players go about deliberately summoning for an oracle type of a particular unit: that's a total waste of gems. (That is, unless Gumi begins to offer rate-ups for certain unit types. They have no reason to do so now, but they might later on.) Instead, I could see this approah working for players who have accured duplicate or unused units over the course of the game, and have some units with conversion buffs.