Pay close attention to all the details.

This is enough to summon 3 Exogenous Demons and 2 Endogenous ones.
Don't worry, they'll not show up until you cast the final spell.

Have in mind that it is just a simple practice to begin with. we've choose 3 and 2, so each of them will take shelter in one angle of the pentagram, and they'll be busy dealing with themselves, so you have a chance to take a look at them.

now...

Please pay close attention my friends...

To summon the first Exogenous Demon, use this spell:

You have to read it out loud 7 times, to summon all 3 Exogenous Demons.

Each time use a different index number , like x1 = ... X2 = ....

When you've finished the 7th spell, the Exogenous Demons will appear all at once.

The Exogenous Demons may look something like this. ( but it depends on the nature of Xs you use )

Well.. now..

DO NOT let them wander around.

To summon the Endogenous ones, use this spell accordingly :

You just need to repeat it 4 times, each time giving ALL the symbols the due index (1,2,3,4)

Once you've finished the 4th spell, they will appear.

Endogenous Demons usually look something like this. ( again, it will depend on the Ys you use.)

Or if you are lucky enough, some may look like this.

Or even this, if you have enough knowledge and wisdom, or if you have spent a lot of time listening to good old Black Sabbath.