Your architects have suggested adding a system of secret tunnels, traps, and ambush points to the Town walls. They say this will help you and your allies defeat more enemies. Upgrading this Knowledge increases the offense of your troops when defending Towns.
| Level | Gold | Soul Shard | Time | Requirements | Troop Offense When Defending Towns | Influence | Hero’s Experience |
| 1 | 110K | 22K | 6w 1d 00h 00m 00s | Infirmary Capacity I 1, Oracle 36 | 1% | 15K | 37.5K |
| 2 | 170K | 32.5K | 63w 6d 00h 00m 00s> 1 Year(s) | Infirmary Capacity I 2, Oracle 36 | 2% | 33K | 47.5K |
| 3 | 225K | 48K | 94w 5d 00h 00m 00s> 1 Year(s) | Infirmary Capacity I 3, Oracle 37 | 3% | 74.5K | 60K |
| 4 | 280K | 71K | 140w 5d 00h 00m 00s> 2 Year(s) | Infirmary Capacity I 4, Oracle 37 | 5% | 170K | 76K |
| 5 | 340K | 110K | 208w 6d 00h 00m 00s> 4 Year(s) | Infirmary Capacity I 5, Oracle 37 | 7% | 380K | 95.5K |
| 6 | 400K | 160K | 310w 1d 00h 00m 00s> 5 Year(s) | Infirmary Capacity I 6, Oracle 38 | 9% | 860K | 120K |
| 7 | 465K | 235K | 460w 4d 00h 00m 00s> 8 Year(s) | Infirmary Capacity I 7, Oracle 38 | 12% | 1.95M | 150K |
| 8 | 565K | 345K | 683w 6d 00h 00m 00s> 13 Year(s) | Infirmary Capacity I 8, Oracle 38 | 16% | 4.4M | 190K |
| 9 | 745K | 515K | 1 015w 4d 00h 00m 00s> 19 Year(s) | Infirmary Capacity I 9, Oracle 39 | 20% | 9.9M | 230K |
| 10 | 1.15M | 760K | 1 508w 1d 00h 00m 00s> 28 Year(s) | Infirmary Capacity I 10, Oracle 39 | 25% | 22.5M | 285K |
| 4.45M | 2.3M | 4 492w 4d 00h 00m 00s> 86 Year(s) | 25% | 40.28M | 1.29M |
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