There are many different methods of a invocation etc. I found some useful info and hopes this helps.
Invocation is when you want that particular entity to step into your body, and you become them, and you absorb those particular energies. In many covens, different pagans will call in a particular quarter, and, when they do, they become that quarter, absorbing that particular energy so much so that they become that Quarter. They then have to stand at that Quarter and guard it, as they are the actual Guardian of that direction. It is interesting but several covens have "words of wisdom" wherein say a pagan, who has invoked a particular Quarter then speaks of wisdom of that element, as the Element is actually speaking through them. The same would be if you invoke the Goddess.
When one draws down the Moon, they are invoking the Goddess into them, and then they are the Goddess. Many of your Wiccan covens say only a male can invoke the Goddess into a female. This is not true. This is solely an idea of Gerald Gardner for male to not only participate in coven rituals but to have some control, when in all actuality, you need no one but yourself to call Her into you. Long ago, when a Witch stood out alone under the bright shining Moon, it was she, the Witch, who called the Moon into herself. Her and her alone.