Monster House (Roshpit)

In this post you will know what Roshan's pit is made of, and how some heroes take advantage over it in their games. First off, let's project how the game itself sees the Dota map: to build pathfinding routes, fog of war, and more. To do this, we need several commands (besides sv_cheats 1):        

1) dota_gridnav_show 1 - shows a navigation grid;     

2) cl_dota_gridnav_show_size 2 - just to make the grid full screen;      

3) dota_show_object_obstructions 1 - shows trees and number of cells they occupy;

 4) dota_show_nav_obstructions 1 - shows obstacles (hills, stones, walls, etc.) and number of cells they occupy, as well as objects (units).  

This is what this beauty looks like in the game:

"Cannot move" is not showed here as obstacles and trees occupy those cells obviously. If you want to see impassible areas - type last two commands but with 0 instead of 1 in the end.

You have 8 trees around Roshpit in total, each of them occupy 4 cells (2x2) though the Ironwood Branch only takes 1 cell (1x1) as well as Hoodwink's acorn. That's just some trivia and is not important here at this point. Instead, it is utterly interesting what lays behind the Roshpit entrance: 

Light blue cells allow you to be both invisible and see inside . Purple cells allow you to be both invisible and see outside.

Now this is the more interesting part. At the very entrance to Rosh there are 13 cells - so-called "phantom spots". If you stay on the phantom spot you are completely unseen to your enemies outside the Roshpit and inside (if not close enough). Depending on which spot you are standing you have the bonus: either you see the inside or the outside areas. In both cases, you are unseen from the outside until the enemy comes closer - there must be 1 (!) cell between you - that's close they have to be.

The left blue dot is an enemy Axe. Batrider cannot see him 2 cells away.

Now axe is seen when Batrider comes 1 step closer (to the edge, and I'm about to break /s)

Why are these spots even exist in Dota? They share the same origin with the pulling/stacking/denying mechanics - it's a bug that became the feature eventually. So-called "ascended glitch". Valve was and still is aware of most bugs but don't fix some of them intentionally leaving them to transform into a feature one day instead.

Phantom spots were a thing even in DotA Allstars though I can't recall when exactly it happenned. The spots then were imported into Dota 2 as a trubute gesture of such a unique element of the game. Patch after patch when Roshpit has been moved the phantom spots were moved with the pit without any additional edits. 

For instance, here's 6.83 patch - the phantom spots are present.

Now look back at the purple/blue cells again and take a closer look at some of them. Specifically these ones:

These 4 cells are the most efficient cells to hide as basically you have a lot of that space to do your dirty job if you are a Techies spammer. The chances that you are unseen are as high as possible in these cells. 

I prefer this one. It's perfect and you should definitely try it in your games.

This skull serves as a navigation point. Just stay an inch above it.

Overall I won't show you that Techies' players hide their mines in one of the phantom spots but show you a few more examples how you can abuse them:

https://www.youtube.com/watch?v=vvpa-b_KqJk - abusing in/out vision at some point of the game on any hero

https://www.youtube.com/watch?v=YP2q9MnsTGY - Zombie Copperfield

https://www.youtube.com/watch?v=SpLN79TO9sk - imagine seeing this in an official match. Killing egg is hard enough, killing the hidden egg is impossible hard.

If we speak about Roshpit in general there is one more thing - walls. You probably tried in one of your games to pin enemies as Mars and the enemies just went through the Roshpit. That happens because Roshpit has only one wall - behind it. Everythings else are just "little hills" so you can't pin anyone to the sides.

As for Pangolier - you can bounce off anything that marked as yellow obstacle showed on any pictures above (dota_show_nav_obstructions 1 console command). Valve sometimes fixes the terrain and there used to be teensy objects that you didn't see but could bounce off of them like this little rock that is already removed:

There are a few more things that I forgot but as of now that's basically it. Thanks for reading.