Settler's Tools: Upgrades the building to rank 2. At rank 2, economy buildings produce 25% more resources, gain 500 additional hit points and cost 300.
Forged Settler's Tools: Upgrades the building to rank 3. At rank 3, external economy buildings produce 20% more resources, gain 500 additional hit points, can temporarily man a defensive tower and cost 400.
The upgrades can be researched from the Dark Iron Forge
Resource Production - This building produces resources. It produces 21 every 12 seconds by default. This number can be modified through upgrades and abilities.
Supply Routes - As you build more economy structures, their individual production becomes less efficient. Once you reach a certain threshold all economy structures will produce less.
5 economy structures or less: 100% production
10 economy structures: 84% production
15 economy structures: 69% production
20 economy structures: 56% production
30 economy structures: 49% production
37 economy structures or more: 44% production
Level 3: Man the Defenses - The workers take up arms. For 20 seconds, the building shoots at nearby enemies but doesn't produce resources.
Tribute to the Iron Crown - Recruitment buildings of Angmar can be upgraded to level 2 and 3 by collecting tribute from the Witch-King's vassals. Orc Camps, Hillmen Villages, Barrows, and Outposts spawn tribute carts every 4 minutes that can be sent into any recruitment structure to upgrade it and generate resources. Passive ability