Cogito, ergo sum
The AssaultRandomizer is a special type of NavigationPoint (UT) used in a small number of Assault maps for UT. It contains only one new property called ToggledCost, a float variable indicating how much extra cost this node imparts on the navigation paths around it. The AssaultRandomizer will toggle this cost on or off by being triggered, and the cost only applies to Bot (UT)s on the attacking team.
For an example of how to place AssaultRandomizers, open AS-OceanFloor in UnrealEd.