Pather

The pather is used to create a path for an NPC to walk along.

Use
Right-clicking an NPC will load the NPC into the pather tool.

Right-clicking on blocks will add that block's coordinate to the NPC's path.

Right-clicking the air will display the full list of coordinates saved to the currently loaded NPC's path. Here, the player can change the order of the coordinates, or delete a coordinate from the path.

NPC
In the AI Tab of the NPC, inside Movement, changing the NPC's movement type to Path will set the NPC to walk along the coordinates saved to their path in order.

Setting them to Looping will cause the NPC to take the shortest path to the first coordinate once they reach the end.

Setting them to Back-tracking will cause the NPC to follow along the path in reverse order once they reach the end.