I received mail from George and, since there are only towers that are obstructing the spider-boss movement, he suggested that we make them passable for spider. This is my replay from the mail I've sent him, see if you also agree:
Click to reveal..
Making the same object passable for spider & non-passable for players is a good idea. The three towers (obstacles for spider movement) are already separated (C3_LBB_PartB.mdl) in level so there is just one thing that should be considered: all my mdl files are set as passable and all collision is achieved through the use of wed blocks with textures set to none. There are two options that I can see: to make towers non-passable and set entity properties to polygon or to cut-out the wed blocks that are relevant for towers, compile them as wmb file & import them in the level as map entities? Can you think of any other solution and if not, which one of these two things do you believe would be better?
The wooden path in the 4th image is connecting the third (back) doors to the arena with the two small posts outside. It will be much clearer when you run the level.
The floating plank is fixed, I've also seen it in the image yesterday when it was too late, everything was already uploaded to Sky Drive As for grid, you are 100 % right. I'm not happy with how it fits & how the edges are blended with the stone-ground. That will all be improved in the level's second version (hopefully the entire chapter will be finalized in a two weeks).
Telescopes are a part of the level's gameplay solution. There is a Gameplay.txt file included in the level's zip, if you like you can check it out.
I'm very glad you like the level.
As for grid, you are 100 % right. I'm not happy with how it fits & how the edges are blended with the stone-ground. That will all be improved in the level's second version (hopefully the entire chapter will be finalized in a two weeks). 
