Strong Mana growth but with average Magic and not much of a moveset to use it. Worth turning into a support for creation or for slime parties, not much else.
They may look boring due to not getting many other skills, but BulbConduit is where it gets interesting, sacrificing a bulb to spread the status effects it had to all surrounding units. This means you can Strengthen your bulb and sacrifice it power up several of your units or Poison it to use it as a poison grenade. This makes Spirit Callers very versatile as support.