Diamond locations.
1) Outside the house with the jukebox under the boarded up window. In rock pile.
2) In Spawn in the corner in rock pile.
3) In wheelbarrow at top of stairs near the door that says "Do not enter".

Final diamond located near pharo power up.

5) Once you have all diamonds, take them back to the room next to the wheelbarrel (with the sealed glass door). In there you can place the diamonds on a table, which will open the glass door next to you.
6) Hit the switch in the room to activate teh Gigant Turrets
7) Make your way to the 4 turrets facing the Giant head. Shoot all four at it to destroy it.
8) Near the teleporter to PaP, another glass door will open revealing the Moon pyramid at the end of the hallway. It is a soul box. Fill it up to continue.
9) The secret "Do Not Enter" door opens up. No clue what to do from here. This might be the end of the easter egg as far as I'm concerned.

Extra things to note:
Filling up all 4 soul boxes around the map unlocks the DG4's next to the PaP teleporter.
Finding and shooting 3 devil head skulls around the map allows you to upgrade the dragon shield underground at the lava river.

@UltzZ Nice, I'll work on the next steps in the next day or so.

In the "Do Not Enter" room there is a paper in a table and you need to axe it. Later when you pass the round a message appears: "A monster lucks in the far" (I don´t know what it means)
And other papers appears in the map that you need to axe:
- In a box near the monster perk
- In the table where the juckebox is
- Under the remington in the beginning
-In the PaP area next to the BubbleGum
... and i died

@APPLEKILLER nice. I did try again to figure out the steps, but I got rid of the axe after doing the diamonds. Guess I'll hand on to it for my next try.

One more paper appears in spawn. Collect that and then
go back to Do Not Enter Room. The Curtain is now gone and you press press F to Aquire Raskovsky's Soul. You will now have the Fireball in your inventory.
Take Raskovsky's Soul to the Moon Pyramid.
The end game is now opened at the Airplane near the shield area. 100000 to finish the end game.

I didn't find the papers :C

@Hibi_TQ

And other papers appears in the map that you need to axe:
- In a box near the monster perk
- In the table where the juckebox is
- Under the remington in the beginning
-In the PaP area next to the BubbleGum
- In Spawn room.

What does "A monster lucks in the far" mean. I've seen the BIG Monster machine in the distance behide the pap machine after the message shows but I know nothing after that. Do i need to do anything more with the monster cuz I did beat the EE. Any ideas?

@Blackfox1988 that is part of the "Super EE" I saw a video where some dude shot the big "M" and the sky turned red/pink, but when I tried nothing happened, so I'm not quite sure.

anyone know what the music ee is called ?