Polished terrain

Is the map going to be surrounded by flat raised terrain or it is just temporary?

If you need (and you probably do) to block the map borders I suggest you going with some proper wow styled mountains that will just blok the path, yet we will look much more appealing from the ground rather than a flat raised terrain.

It definitely won't look like it looks now (btw, on another screenshot you should be able to see I already started creating mountains from that flat terrain -

). I will finish those mountains - somehow - to make it look better. Anyway, noone will ever see that map from above, so its not that important to me now. I also don't want to rely just on terrain and collision - I really need to make damn sure players won't get ANYWHERE where they should not. Which means I will have to use many invisible collision walls to prevent them from climbing on rocks, going though forests which should be impassible and so on.

You can make a wmo for collision.  Such as the one from SoTA battleground. If you're interested in such a way of adding collision to your map I can help you with getting your terrain in blender so you could build your collision.

Thanks, that definitely sounds interresting, but my collisions will be based more on M2s than on terrain itself. I need to finish spawn of forests, then I can start thinking about collisions. Or would it be possible to import it into Blender even with models on that ADT?

Aaand just btw, I am familiar with Maya, but I can't create even a single polygon in that damned Blender. I would have to learn how to use that program and honestly, I am really uncomfortable whenever I have to use it.