#Edit 1 - If you play the level with someone who has the mission achievement will pop for you either
#Edit 2 - Some guys told me today (16/12/20) that they deleted the location of the secret level. I can not confirm because I unlocked it before..Finally, after
13 tries, I was able to find the
Colossal Rampart's map.
Remember it is really rare to find this one, because you have to have some luck
*RNG* So here's what you gotta do:
1. Choose
Windswept Peaks level
2. You need to reach the arena where there are 3 gates (after you get out of the 2nd elevator)
3. After you clear the arena go out and show the map by
and see if you have map like in the
picture (link)https://photos.app.goo.gl/Z4omH8mGN3qvzMTE64. If you have the luck you will able to find a big gold gate/door there, just go over to the gate and fall in front of it and go inside.
5. Go straight the way, untill you will see the map on table/brick (there will be a ambush too)
6. Pick the map and that's all, you will unlock the secret level
7. Just complete the Colossal Rampart mission and you are done
Best of luckIf you have any questions ask here, or it works if you can
add me and I will play the mission with you, it will pop for you too.