Intellect is still your primary stat, it provides you with Spell Power and increases the damage of your spells.
Haste is by far the best stat for Demonology Warlocks, it decreases the cast speed of all your spells and also effects the amount of casts your Demons can do before despawning. It also increases the amount of ticks your Doom will tick. Haste also helps with smoothing the rotation out as it helps increase Soul Shard generation which means you can spend them more frequently without harsh consequences.
Critical Strike increases your chance to critically hit with all spells and abilities.
Versatility is a flat out damage done increase and damage taken reduction.
Kazzak's Final Curse increases Doom damage by 5% for every demon you have active. Super strong legendary when you can use Hand of Doom effectively and have lots of Dooms ticking. Overall the best legendary to get your hands on especially when combining with Impending Doom for best DPS results.
Sin'dorei Spite increases damage by 15% for 25 seconds after summoning Doomguard or Infernal. This legendary is very good in certain situations, especially if a fight has a hard damage check. On farm when kill times are also really quick this legendary jumps in value quite a lot. Still a good legendary to have regardless and is around 3rd for progress fights.
Wilfred's Sigil of Superior Summoning reduces the cooldown of Summon Doomguard by 2.0 seconds for every Dreadstalker or Imp you summon. Can be decent if there's a lot of targets as you will be casting more pets however single targets its pretty weak.
Kil'jaeden's Burning Wish launches a vortex towards the target exploding within a 10 yard radius for 634,000 fire damage. Legendary is weak in general as it takes up a trinket slot however can be really nice for mythic+.
Best 3 legendaries which you want to try and get to boost your DPS the most are:
T19 Set Pieces are really strong for all Warlock Specilizations.
T19 2P however is no where near as strong as the 4 Piece.
0-2P is only a 1.5% Increase however 0-4P is 7.1% increase so you can see how big the jump is. Try and get your hands on 4P as soon as possible to get the most out of your Demonology Warlock. Also stats are really important as Demonology, as you can see in the 'stats' Section that Intellect is ranked 4th Priority so try and optimize your gear well stat wise.
The best 4 trinkets that you really want as a Demonology Warlock are as follows:
- Whispers in the Dark (Gul'dan)
- Erratic Metronome (Chronomatic Anomaly)
- Brinewater Slime in a Bottle with Haste/Crit (Helya)
- Chrono Shard (Arcway Mythic+)
Races are a lot less beneficial than they use to be however the best DPS ones are;
Rings: Enchant Ring - Binding of Haste x2
Socket Quick Dawnlight in all.
Flask: Flask of Whispered Pact
Food: Azshari Salad