Defending a Fortress is a matter of honor for Heroes. In the name of their Jarl, they will do everything they can to thwart enemy attempts to capture the location. Upgrading this Knowledge increases your troops' defense when guarding Fortresses.
| Level | Gold | Soul Shard | Time | Requirements | Troop Defense When Guarding Fortresses | Influence | Hero’s Experience |
| 1 | 175K | 34.5K | 68w 3d 00h 00m 00s> 1 Year(s) | Troop Defense When Capturing Fortresses III 1, Oracle 36 | 3% | 19K | 48.5K |
| 2 | 265K | 51.5K | 101w 5d 00h 00m 00s> 1 Year(s) | Troop Defense When Capturing Fortresses III 2, Oracle 36 | 9% | 43K | 61K |
| 3 | 355K | 76K | 150w 6d 00h 00m 00s> 2 Year(s) | Troop Defense When Capturing Fortresses III 3, Oracle 37 | 15% | 97K | 77K |
| 4 | 445K | 115K | 224w 1d 00h 00m 00s> 4 Year(s) | Troop Defense When Capturing Fortresses III 4, Oracle 37 | 23% | 220K | 97K |
| 5 | 540K | 170K | 332w 5d 00h 00m 00s> 6 Year(s) | Troop Defense When Capturing Fortresses III 5, Oracle 38 | 32% | 495K | 125K |
| 6 | 635K | 250K | 494w 1d 00h 00m 00s> 9 Year(s) | Troop Defense When Capturing Fortresses III 6, Oracle 38 | 44% | 1.15M | 155K |
| 7 | 740K | 370K | 733w 5d 00h 00m 00s> 14 Year(s) | Troop Defense When Capturing Fortresses III 7, Oracle 39 | 59% | 2.55M | 190K |
| 8 | 895K | 550K | 1 089w 3d 00h 00m 00s> 20 Year(s) | Troop Defense When Capturing Fortresses III 8, Oracle 39 | 78% | 5.7M | 235K |
| 9 | 1.2M | 815K | 1 617w 6d 00h 00m 00s> 31 Year(s) | Troop Defense When Capturing Fortresses III 9, Oracle 40 | 100% | 13M | 290K |
| 10 | 1.85M | 1.25M | 2 402w 3d 00h 00m 00s> 46 Year(s) | Troop Defense When Capturing Fortresses III 10, Oracle 40 | 130% | 29M | 355K |
| 7.1M | 3.68M | 7 215w 3d 00h 00m 00s> 138 Year(s) | 130% | 52.27M | 1.63M |
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