The phrase "call down" can have a couple of different meanings and uses in English. Let's break it down to make it easier to understand.
To Scold or Censure: When someone calls down someone else, it means they are scolding or criticizing them, often in a severe or angry way.
To Summon or Bring into Existence: In a more magical or spiritual sense, to call down something means to bring it into action or to summon it, often as if by magic.
In conclusion, "call down" can mean to reprimand someone severely or to summon something, often with a sense of urgency or magic. It is useful to understand the context to know which meaning is intended.