When preparing siege engines for a march, engineers add extra reinforcement to their frames and wheels in order to reduce the chance of them breaking. Upgrading this Knowledge increases the defense of your siege engines during an attack.
| Level | Gold | Soul Shard | Time | Requirements | Siege Defense During an Attack | Influence | Hero’s Experience |
| 1 | 115K | 22.5K | 44w 6d 00h 00m 00s | Siege defense against melee 1, Oracle 36 | 1% | 15.5K | 41K |
| 2 | 175K | 33.5K | 66w 4d 00h 00m 00s> 1 Year(s) | Siege defense against melee 2, Oracle 36 | 4% | 35K | 51K |
| 3 | 235K | 49.5K | 98w 5d 00h 00m 00s> 1 Year(s) | Siege defense against melee 3, Oracle 37 | 8% | 79K | 64K |
| 4 | 295K | 73.5K | 146w 4d 00h 00m 00s> 2 Year(s) | Siege defense against melee 4, Oracle 37 | 13% | 180K | 80K |
| 5 | 350K | 110K | 217w 5d 00h 00m 00s> 4 Year(s) | Siege defense against melee 5, Oracle 38 | 18% | 405K | 99.5K |
| 6 | 415K | 165K | 323w 1d 00h 00m 00s> 6 Year(s) | Siege defense against melee 6, Oracle 38 | 25% | 910K | 125K |
| 7 | 485K | 245K | 479w 6d 00h 00m 00s> 9 Year(s) | Siege defense against melee 7, Oracle 39 | 34% | 2.05M | 155K |
| 8 | 585K | 360K | 712w 4d 00h 00m 00s> 13 Year(s) | Siege defense against melee 8, Oracle 39 | 45% | 4.65M | 195K |
| 9 | 775K | 535K | 1 058w 2d 00h 00m 00s> 20 Year(s) | Siege defense against melee 9, Oracle 40 | 58% | 10.5M | 235K |
| 10 | 1.2M | 790K | 1 571w 3d 00h 00m 00s> 30 Year(s) | Siege defense against melee 10, Oracle 40 | 75% | 24M | 290K |
| 4.63M | 2.38M | 4 719w 5d 00h 00m 00s> 90 Year(s) | 75% | 42.82M | 1.34M |
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