Thought to be one way the Great Race protected themselves from enemy agents.
Slows down infiltration time by 3 hours per level of the gauntlet. While spies are mired and spending time trying to find their way through the gauntlet, they cannot attack and are vulnerable to security sweeps. Because spies from allies don't "infiltrate", they are immune to Gratch's Gauntlet.
The actual practical usefullness of this glyph building is often highly debated. Most arguements revolve around the fact that this building does not actualy catch incoming spies and just slows them down. Still the player is actually required to run security sweeps to catch mirred down spies. Othere debates tend to center around what level to build it to whether level 8 is suffiecent to keep spies mirred down for 24 hours, or to keep them mirred down for a full 90 hours.
Note: previously this building was in-effective, but since the zero-travel-time spy bug has been fixed Gratch's Gauntlet should now work correctly.