Warlock · Demonology · tier 5 · from level 30

Demonic Knowledge

+234 Bane of Doom

3/3 · level 60 · per cast · with a demon · and 17 more

Demonic Knowledge 123

Rank 3/3

Increases your spell damage and your Demon pet's spell damage by up to 100% of your level while you have a summoned Demon pet active.

Bane of Doom +234 Bane of Agony +93.5 Corruption +70.3 Inferno +58.6 Soul Fire +58.6 Wrack +50.3 Shadow Bolt +50.2 Immolate +49.8 Incinerate +41.8 Drain Soul +29.3 Siphon Life +29.3 Drain Life +29.3 Searing Pain +25.1 Shadowburn +25.1 Conflagrate +25.1 Rain of Fire +19.5 Hellfire +19.3 Death Coil +12.5

Averages, counting crits and misses, for a level 60 Warlock with a typical weapon and no other gear or buffs, against a target your level. Worked out from the game's own data, the same way as the Foresight addon.