Doctor Proctor
First Post
Walls are temporary delays for the monsters, who can go around or through them. Orbs are a permanent delay. It's still too powerful IMO.
Wall of Fire is a sustain minor, the same as the orb. So in terms of the amount of time they can exist, they're the same.
Granted, you can move through a wall of fire....but it costs 3 extra squares of movement, does 3d6+INT damage and an additional 1d6+INT if you're don't move far enough and start your next turn adjacent to it. So yeah, you can get around the wall, but only at great cost. Plus, if you were trying to block a small area, such as a 10' hallway, you could snake the wall such that the enemy has to go through 2 or 3 squares of the fire wall. This would result in massive amounts of damage because you might not even be able to make it all the way through in a single round!
The point is, while they're not the same exactly, they create similar effects. They can isolate enemies and allow the party to split up the encounter at-will. The walls can also completely distort the terrain the DM made by creating new terrain that must be avoided. With something like Web, you can even further distort the DM's carefully crafted terrain. That one is an auto-hit as well, since anyway ending their movement is automatically immobilized.