Destruction Warlock

Intellect is the most important stat for a Destruction Warlock as it increases the damage of your spells, this is why Destruction Warlocks just want as high item level gear as possible.

Haste decreases the cast speed of you spells. It also buffs Immolate as the tick rate increases and the cooldown of Conflagrate is decreased. The more haste you have, the better Soul Shard regeneration you will have. Haste also scales with your demons.

Critical Strike increases your chance to critically hit with all spells and abilities. Chaos Bolt always ciritically hits and its damage is increased by your ciritical Strike. Immolate criticals also have double chance to produce a Soul Shard.

Mastery: Chaotic Energies increases your damage dealt by a random amount as well as reducing damage taken by a random amount. Its between 0 and the maximum amount which dpeends on your mastery rating.

Versatility is just a flat damage increased and damage reduction, in which your demons scale with too.

 

Gear

Legendaries

Lessons of Space-Time increases all of your damage by 10% while your Dimensional Rifts are active. This is the strongest legendary for single target.

Feretory of Souls gives Fire spells a 10% chance to generate a Soul Shard. Very strong for all situations.

Sin'dorei Spite is the second best legendary and causes you and your minions to deal 15% increased damage for 25 seconds after casting Summon Doomguard or Summon Infernal.

Odr, Shawl of the Ymirjar causes enemies marked by Havoc to take 8% increased damage from your single target spells. Very strong on fights where you can take full advantage of.

Magistrike Restraints gives Chaos Bolt a 20% chance to strike an additional enemy within 30 yards. Decent legendary, especially on add fights where there are a lot of high priority targets.

Alythess's Pyrogenics causes enemies affected by Rain of Fire to take 10% increased damage from Fire spells. Worst legendary overall, not much use.

Kil'jaeden's Burning Wish takes up a valuable trinket slot but sports a high amount of passive stats and a useful on use burst effect.

Best Single Target Combination: Feretory of Souls + Sin'dorei Spite/Lessons of Space-Time.

Best Cleave Combination: Feretory of Souls + Magistrike Restraints.

Set Pieces

T19 bonuses are really strong for Warlocks

T19 2 piece is worth losing 10-15 ilvl on items for, it is even strong in cleave situations as it helps get more Chaos Bolts out.

T19 4 piece is worth losing 40+ ilvl on items for, it is a 10% DPS increase, try and get your hands on this ASAP.

A general rule for warlocks if its 10 ilvl upgrade ALWAYS equip it, as ilvl is everything for a destruction warlock.

Trinkets

The main 4 trinkets in which you want to try and get your hands on are as follows

1. Whispers in the Dark (Gul'dan)
2. Erratic Metronome (Chronomatic Anomaly)
3. Brinewater Slime in a Bottle with Haste or Crit (Helya)
4. Chrono Shard or any other int/haste trinket from Mythic+

Races are a lot less beneficial than they use to be however the 'best' ones for DPS are;

Horde: Troll

Alliance: Worgen/Human

BiS Enchants

Neck: Enchant Neck - Mark of the Claw

Cloak: Enchant Cloak - Binding of Intellect

Rings: Enchant Ring - Binding of Haste

BiS Gems

Socket Quick Dawnlight in all.

Flask: Flask of the Whispered Pact

Potion: Potion of Prolonged Power or Potion of Deadly Grace if you need to burst an add which is really important.

Food: Azshari Salad