Key trapping is a time-wasting method that is used to force raiders to bring a key into a room in order to test it. In order to test a set of keys, it is best to use multiple identical rooms so that raiders are forced to harvest multiple sets of the same key (thus wasting time). Key trapping will be illustrated using the example below. This example is pulled from a segment from Xunti's current maze (Blue arrows are where portals take you, and black arrows are one-way exits).
As you can see in this example, raiders move from one part of the maze into this part. In the random room they will find 4 exits to 4 side rooms (A-D) and two exits to jail. Since each room (A, B, C and D) look the same. Raiders must bring key 1 into each of the rooms in order to test the north/south doors. Three of these rooms do nothing (B, C, D) act as a trap for key 1, thereby preventing raiders from finding room A.