Impregnable is a side quest which offers rewards for upgrading the Wall.

Impregnable — Upgrade the Wall (edit)
Requirement Reward
Upgrade Wall to Level 2 Resource icon food.png 2,500
Resource icon wood.png 1,750
Upgrade Wall to Level 3 Resource icon food.png 3,250
Resource icon wood.png 6,000
Upgrade Wall to Level 4 Resource icon food.png 5,250
Resource icon wood.png 7,750
Upgrade Wall to Level 5 Resource icon food.png 25,250
Resource icon wood.png 26,750
Upgrade Wall to Level 6 Resource icon food.png 17,500
Resource icon wood.png 21,000
Resource icon stone.png 9,500
Upgrade Wall to Level 7 Resource icon food.png 21,250
Resource icon wood.png 24,750
Resource icon stone.png 12,250
Upgrade Wall to Level 8 Resource icon food.png 26,750
Resource icon wood.png 31,500
Resource icon stone.png 16,500
Upgrade Wall to Level 9 Resource icon food.png 29,250
Resource icon wood.png 30,000
Resource icon stone.png 17,000
Upgrade Wall to Level 19 Resource icon food.png 469,000
Resource icon wood.png 548,750
Resource icon stone.png 331,250
Upgrade Wall to Level 20 Resource icon food.png 704,750
Resource icon wood.png 824,250
Resource icon stone.png 498,000
Upgrade Wall to Level 22 Resource icon food.png 1,585,750
Resource icon wood.png 1,856,500
Resource icon stone.png 1,122,250
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