So the spell sat when you direct it it moves until it moves into a square with a creature. When you don't it stays at rest and crackles with lightning. My question is what if a creature still occupies the square, Does the creature have to make a save on your turn to avoid damage. Say for instance the creature can't move out of the square. Does the spell simply go inactive until you control it again or would it continue to damage the creature until the spell is moved or it moves out of the space where the spell is?