I agree that burrowing is impractical. Even the sand dragon will not be able to use it because it will be an almost guaranteed loss. The problem is that an opponent would only need to keep him out one round. Which reminds me of another problem. I don't like the idea of forcing someone out of the VZ. If an opponent tries to enter the VZ, but is prevented, then that should 'count' as entering the VZ (for that round). In other words, it may not negate the loss condition, but it would extend it one more round as long as the combatant makes every effort to enter. This extension would continue. This also eliminates the "block in the VZ with walls of force" bologna and, more importantly, the cheap victory.
As we've seen, swimmers have had reasonable success swimming under the VZ to enter from both sides. Burrowers do not enjoy the same luxury, and I'm not just saying this because of sand dragons. I think a horizontal VZ strip would not work well because it then eliminates swimmers and burrowers. To accommodate Gansk's issue of not even being able to charge, perhaps extend the water/sand strips by 10ft (to 30ft wide) and then have the VZ be 80ft long, 20ft wide in the center, extending 10ft over the water/sand. If there's a slow creature that stands in the middle of an 80ft wide strip and still can't charge to either end (to be within Reach), then oh well.
