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 | 105K | 21K | 41w 1d 00h 00m 00s | Troop Defense When Capturing Fortresses I 1, Oracle 36 | 1% | 19K | 48.5K |
| 2 | 160K | 31K | 8w 5d 00h 00m 00s | Troop Defense When Capturing Fortresses I 2, Oracle 36 | 4% | 43K | 61K |
| 3 | 215K | 46K | 90w 4d 00h 00m 00s> 1 Year(s) | Troop Defense When Capturing Fortresses I 3, Oracle 36 | 8% | 97K | 77K |
| 4 | 270K | 68K | 134w 3d 00h 00m 00s> 2 Year(s) | Troop Defense When Capturing Fortresses I 4, Oracle 37 | 13% | 220K | 97K |
| 5 | 325K | 105K | 199w 5d 00h 00m 00s> 3 Year(s) | Troop Defense When Capturing Fortresses I 5, Oracle 37 | 19% | 495K | 125K |
| 6 | 380K | 150K | 296w 3d 00h 00m 00s> 5 Year(s) | Troop Defense When Capturing Fortresses I 6, Oracle 37 | 26% | 1.15M | 155K |
| 7 | 445K | 225K | 440w 2d 00h 00m 00s> 8 Year(s) | Troop Defense When Capturing Fortresses I 7, Oracle 37 | 34% | 2.55M | 190K |
| 8 | 540K | 330K | 653w 5d 00h 00m 00s> 12 Year(s) | Troop Defense When Capturing Fortresses I 8, Oracle 38 | 45% | 5.7M | 235K |
| 9 | 710K | 490K | 970w 5d 00h 00m 00s> 18 Year(s) | Troop Defense When Capturing Fortresses I 9, Oracle 38 | 56% | 13M | 290K |
| 10 | 1.1M | 730K | 1 441w 3d 00h 00m 00s> 27 Year(s) | Troop Defense When Capturing Fortresses I 10, Oracle 38 | 70% | 29M | 355K |
| 4.25M | 2.2M | 4 277w 1d 00h 00m 00s> 81 Year(s) | 70% | 52.27M | 1.63M |
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