How To Summon Or Invoke A Demon
Under normal circumstances you should never say a demon's name aloud, it can be taken as an invitation by the demon. Of course, in this situation it is intend as an invite, so repeat the name over and over. When you feel the time is right, you should start to recite words or incantations that are meaningful to you. The power isn't so much in the specific words you are saying, but the belief behind them. If you know the demon's name, you should use it in these incantations.
You could try phrases like:
In the name of Satan, open the gates of hell and greet me, come forward, show us you're here.
I invite the forces of darkness to bestow their infernal power upon me.
Come forward forces of darkness and greet me.
I invoke thee Astaroth.
Once a demon makes its presence known, you should tell it exactly why you have summoned it. You need to get the demon on your side and chances are you're not the first paranormal investigators on their patch. They might already feel like a performing monkey. Demons are unlikely to be happy existing for no other purpose than to amuse you, so tell them you're not here to mock them and that you want to communicate. Ask the demon if they need help or have a message, ask them to show them a sign they are here so that you can talk to them, perhaps even to help them move on.
Demonic entities are usually only able to give very subtle clues to the fact that they are present. They might use our energy to communicate through a Ouija board, knock over an object, tap on a hard surface, or make a sound in someone's ear. It's unusual to hear a loud noice, a clear voice, or see an object deliberately being moved for any sustained period of time.
So, we can assume that demons have to muster up a lot of energy in order to give us these signs. Therefore you should thank the demon for their efforts if they do something that you've asked them to do. Give them encouragement, let them know that what they've shown you is great, but ask them to do a little more if they can.
Be sure not to shut the session down prematurely. One common mistake is to say things like "give us a sign that you're here, then we'll leave you alone." To be true to your word, if the demon does then give you a sign then you're going to have to pack up and end your investigation. Otherwise you'll have lied and the demon is unlikely to trust you again or do as you ask.
At this point you might want to switch to another method of communication such as a Ouija board, a spirit box, a digital audio recorder in order to capture EVPs or any other method you are comfortable using. This might enable you to have a more meaningful conversation with the demon. Below is a list of example questions and phrases that you can use to try to encourage the demon to communicate with you. You shouldn't copy these exactly, it is better to be yourself and talk in a natural and open way as you normally would.
If you can hear me, tap on the floor.
Can you make a noise to let us know you are here with us?
If you're here can you show yourself to me?
Can you make a noise?
Can you throw something?
Can you copy me? [then tap on a surface or whistle]
My name is XXX, can you tell me your name?
Tell us who you are, introduce yourself please.
If there's somebody here with us now, can you walk towards us?
Are you happy for us to be here? Two taps for yes, one for no.
Can you come and talk to us?
Of course, if you establish a dialogue with a demon then you can ask more in depth questions. Try to ask questions that no one in the room would know the answers to so you can rule out fakery or people subconsciously effecting the outcome.