Q u o t e: In D2, the extent of harm the terrain or background could inflict was with random traps. I'm wondering, will there be more creative harmful terrain? It would be interesting if there were swamps where walking into the wrong places could poison you, or shallow water in cold locations that slow you down. Things like this could add a strategic element; monsters might try and funnel you towards harmful terrain and you have to watch out for this and avoid landing in a position where they can checkmate you. You could also have enemies with knock back effects trying to force you into a bad position.
I think this would be especially good if there were occasionally instant death types of terrain, like ledges at high altitude, or pits with spikes. Players (particularly hardcore players) would have to be especially talented in treading carefully, and engaging the enemy intelligently.
Another thought; there could be entire locations whose environment is harmful. For example, one whose air is especially hot, and slowly drains your life, forcing you to move quickly. Of course, the challenge of these locations would be facilitated by the absence of TPs, so one would have to make sure they're prepared and focused before passing through them.
Will there be harmful terrain? And if so, what do you think of these ideas? I think they would add exciting dynamics to the game.
Overall global terrain (in the game world or in a zone/location) debuffs is just bad, imo... nothing is gained from it and the player has to deal with the annoyance of constant negative effects. It is like dealing with a Health Globe that degenerates over time... not fun, imo.
As to what concerns specific positions and the player skill necessary to navigate them, it CAN be interesting. However as far as being cornered or knocked back into them by monsters, traps are still more than enough, specially because if the intention is to condition the players behaviour, then the dangers need to be extremely noticeable (so the player knows they should not go there).
Instant death is just a terrible, terrible idea in most cases.
However a debuff in movement speed while fighting, for instance, in a marsh as you suggest (knee/waist high water) might be interesting if the encounter with the specific location monsters is designed around them having the ability to move far quicker than the player... like some sort of amphibian lizard (heh... just noticed I could have said crocodile/alligator *rolls eyes to himself*).
Q u o t e: On the wind a shout
The barbarian strikes down
Flesh renders from bone