Forbidden arts and dark Knowledge will teach your killers to strike the most vulnerable spots and deliver deathblows! Upgrading the Knowledge increases the damage caused by your killers.
| Level | Lumber | Iron | Stone | Silver | Gold | Time | Requirements | Increased Slayer Offense | Influence | Hero’s Experience |
| 1 | 2.5K | 1.9K | 2.5K | 3K | 665 | 03h 00m 00s | 1 | 150 | 15K | |
| 2 | 5K | 3.75K | 5K | 7.5K | 1.1K | 07h 00m 00s | Oracle 4 | 3 | 375 | 30K |
| 3 | 10K | 7.5K | 10K | 19K | 1.75K | 15h 00m 00s | Oracle 6 | 7 | 940 | 45K |
| 4 | 20K | 15K | 20K | 47K | 3.2K | 1d 09h 00m 00s | Oracle 8 | 13 | 2.35K | 60K |
| 5 | 40K | 30K | 40K | 120K | 6.15K | 3d 00h 00m 00s | Oracle 10 | 21 | 5.9K | 75K |
| 6 | 80K | 60K | 80K | 295K | 13.5K | 1w 00h 00m 00s | Oracle 12 | 31 | 15K | 90K |
| 7 | 160K | 120K | 160K | 735K | 24.5K | 2w 1d 00h 00m 00s | Oracle 14 | 46 | 37K | 105K |
| 8 | 320K | 240K | 320K | 1.85M | 44K | 4w 4d 00h 00m 00s | Oracle 16 | 66 | 92K | 120K |
| 9 | 640K | 480K | 640K | 4.6M | 79K | 9w 6d 00h 00m 00s | Oracle 18 | 91 | 230K | 135K |
| 10 | 1.3M | 960K | 1.3M | 11.5M | 145K | 21w 4d 00h 00m 00s | 131 | 575K | 150K | |
| 2.58M | 1.92M | 2.58M | 19.18M | 318.87K | 39w 6d 10h 00m 00s | 131 | 958.72K | 825K |
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