Studying the plans of Fortresses and secret annals about sieges has helped warlords to develop new tactics that will allow them to achieve better results with fewer casualties. Upgrading this Knowledge increases your army's defense in battles for Fortresses.
| Level | Gold | Soul Shard | Time | Requirements | Troop Defense in Fortresses | Influence | Hero’s Experience |
| 1 | 175K | 34.5K | 68w 3d 00h 00m 00s> 1 Year(s) | Troop Defense When Guarding Fortresses III 1, Oracle 36 | 1% | 19K | 48.5K |
| 2 | 265K | 51.5K | 101w 5d 00h 00m 00s> 1 Year(s) | Troop Defense When Guarding Fortresses III 2, Oracle 36 | 4% | 43K | 61K |
| 3 | 355K | 76K | 150w 6d 00h 00m 00s> 2 Year(s) | Troop Defense When Guarding Fortresses III 3, Oracle 37 | 8% | 97K | 77K |
| 4 | 445K | 115K | 224w 1d 00h 00m 00s> 4 Year(s) | Troop Defense When Guarding Fortresses III 4, Oracle 37 | 13% | 220K | 97K |
| 5 | 540K | 170K | 332w 5d 00h 00m 00s> 6 Year(s) | Troop Defense When Guarding Fortresses III 5, Oracle 38 | 19% | 495K | 125K |
| 6 | 635K | 250K | 494w 1d 00h 00m 00s> 9 Year(s) | Troop Defense When Guarding Fortresses III 6, Oracle 38 | 26% | 1.15M | 155K |
| 7 | 740K | 370K | 733w 5d 00h 00m 00s> 14 Year(s) | Troop Defense When Guarding Fortresses III 7, Oracle 39 | 34% | 2.55M | 190K |
| 8 | 895K | 550K | 1 089w 3d 00h 00m 00s> 20 Year(s) | Troop Defense When Guarding Fortresses III 8, Oracle 39 | 45% | 5.7M | 235K |
| 9 | 1.2M | 815K | 1 617w 6d 00h 00m 00s> 31 Year(s) | Troop Defense When Guarding Fortresses III 9, Oracle 40 | 56% | 13M | 290K |
| 10 | 1.85M | 1.25M | 2 402w 3d 00h 00m 00s> 46 Year(s) | Troop Defense When Guarding Fortresses III 10, Oracle 40 | 70% | 29M | 355K |
| 7.1M | 3.68M | 7 215w 3d 00h 00m 00s> 138 Year(s) | 70% | 52.27M | 1.63M |
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