The smithy is a perpetual spot type that when controlled by the player will give the following benefits:

Level⠀⠀⠀⠀⠀⠀⠀1⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀2⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀3
Tribute⠀⠀⠀⠀⠀⠀Every 15 turns⠀⠀⠀⠀⠀⠀Every 10 turns⠀⠀⠀⠀⠀Every 5 turns
Visit rewards⠀⠀Grey items⠀⠀⠀⠀⠀⠀⠀⠀Green items⠀⠀⠀⠀⠀⠀⠀Blue items
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀Improve smithy⠀⠀⠀⠀⠀Improve smithy⠀⠀⠀⠀⠀-
Visit cooldown⠀10 for item⠀⠀⠀⠀⠀⠀⠀⠀10 for item⠀⠀⠀⠀⠀⠀⠀⠀10 for item
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀3 after improvement⠀⠀3 after improvement⠀⠀-
Defenders⠀⠀⠀⠀12 weak units⠀⠀⠀⠀⠀⠀16 good units⠀⠀⠀⠀⠀⠀20 man doomstack

If controlled by the AI, (the AI will control most smithies except the Kislev western one that is initially controlled by Kostaltyn), the smithy will provide a random item every 5 turns for the AI faction controlling it and have a 20 man doomstack garrison protecting it.

Visit them to improve every single one of them or to obtain an ancillary depending on their levels. Upgrading it from level 1 to 2 will require 20000 of your treasury. From level 2 to 3 will require 40000 of your treasury.

Disclaimer: Version 1 of the smithy spot. It is still feature incomplete. Will update this description in the future with the other 3 missing features as I update them.