Sentinel Checkpoint is a security gate located near the entrance of Nexus Tower. Whenever a player approaches and enters one of the gateways, they are scanned by a beam.
Two baggage scanners are set up, one each for players entering and leaving the Sentinel area of the tower. They are large enough for players to enter, and should they get close enough, they will be sucked in one end and spat out the other, glowing green from the x-ray. Sometimes a glitch happens and players can't move.
Yawny Goodknight is supposed to monitor those entering and leaving, however he spends most of his time asleep, only stirring when players wake him using Speedchats nearby.