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 | 105K | 21K | 41w 1d 00h 00m 00s | Troop Defense When Guarding Fortresses I 1, Oracle 36 | 1% | 16K | 40K |
| 2 | 160K | 31K | 8w 5d 00h 00m 00s | Troop Defense When Guarding Fortresses I 2, Oracle 36 | 2% | 35.5K | 50.5K |
| 3 | 215K | 46K | 90w 4d 00h 00m 00s> 1 Year(s) | Troop Defense When Guarding Fortresses I 3, Oracle 36 | 4% | 80.5K | 64K |
| 4 | 270K | 68K | 134w 3d 00h 00m 00s> 2 Year(s) | Troop Defense When Guarding Fortresses I 4, Oracle 37 | 6% | 185K | 80.5K |
| 5 | 325K | 105K | 199w 5d 00h 00m 00s> 3 Year(s) | Troop Defense When Guarding Fortresses I 5, Oracle 37 | 8% | 410K | 105K |
| 6 | 380K | 150K | 296w 3d 00h 00m 00s> 5 Year(s) | Troop Defense When Guarding Fortresses I 6, Oracle 37 | 11% | 925K | 130K |
| 7 | 445K | 225K | 440w 2d 00h 00m 00s> 8 Year(s) | Troop Defense When Guarding Fortresses I 7, Oracle 37 | 15% | 2.1M | 160K |
| 8 | 540K | 330K | 653w 5d 00h 00m 00s> 12 Year(s) | Troop Defense When Guarding Fortresses I 8, Oracle 38 | 19% | 4.75M | 195K |
| 9 | 710K | 490K | 970w 5d 00h 00m 00s> 18 Year(s) | Troop Defense When Guarding Fortresses I 9, Oracle 38 | 24% | 11M | 240K |
| 10 | 1.1M | 730K | 1 441w 3d 00h 00m 00s> 27 Year(s) | Troop Defense When Guarding Fortresses I 10, Oracle 38 | 30% | 24M | 295K |
| 4.25M | 2.2M | 4 277w 1d 00h 00m 00s> 81 Year(s) | 30% | 43.5M | 1.36M |
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