Every fight, every skirmish, every battle for a Fortress leaves scars on a Viking's body. But this makes the Viking even stronger and more resilient. Upgrading this Knowledge increases your army's health in battles for Fortresses.
| Level | Gold | Soul Shard | Time | Requirements | Troop health in Fortresses | Influence | Hero’s Experience |
| 1 | 140K | 28K | 54w 6d 00h 00m 00s> 1 Year(s) | Troop Health When Guarding Fortresses II 1, Oracle 36 | 1% | 19K | 48.5K |
| 2 | 215K | 41K | 81w 2d 00h 00m 00s> 1 Year(s) | Troop Health When Guarding Fortresses II 2, Oracle 36 | 3% | 43K | 61K |
| 3 | 285K | 61K | 120w 5d 00h 00m 00s> 2 Year(s) | Troop Health When Guarding Fortresses II 3, Oracle 37 | 6% | 97K | 77K |
| 4 | 360K | 90.5K | 179w 2d 00h 00m 00s> 3 Year(s) | Troop Health When Guarding Fortresses II 4, Oracle 37 | 9% | 220K | 97K |
| 5 | 430K | 135K | 266w 1d 00h 00m 00s> 5 Year(s) | Troop Health When Guarding Fortresses II 5, Oracle 37 | 14% | 495K | 125K |
| 6 | 505K | 200K | 395w 2d 00h 00m 00s> 7 Year(s) | Troop Health When Guarding Fortresses II 6, Oracle 38 | 19% | 1.15M | 155K |
| 7 | 595K | 300K | 83w 6d 00h 00m 00s> 1 Year(s) | Troop Health When Guarding Fortresses II 7, Oracle 38 | 25% | 2.55M | 190K |
| 8 | 715K | 440K | 871w 4d 00h 00m 00s> 16 Year(s) | Troop Health When Guarding Fortresses II 8, Oracle 38 | 32% | 5.7M | 235K |
| 9 | 950K | 655K | 1 294w 2d 00h 00m 00s> 24 Year(s) | Troop Health When Guarding Fortresses II 9, Oracle 39 | 40% | 13M | 290K |
| 10 | 1.45M | 970K | 274w 4d 00h 00m 00s> 5 Year(s) | Troop Health When Guarding Fortresses II 10, Oracle 39 | 50% | 29M | 355K |
| 5.65M | 2.92M | 3 621w 6d 00h 00m 00s> 69 Year(s) | 50% | 52.27M | 1.63M |
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