On casting wall of greater dispel magic, a wall was created. This wall was invisible, so invisible in fact that it was impossible to see with a see invisibility spell. It was also impossible to feel and one could easily pass through it as though nothing was there. However, people who passed through this wall came under the effect of a targeted greater dispel magic effect. A creature that was summoned could be dissipated by this spell. A true seeing allowed a person to see both the invisible wall and its capacities.