Translated automatically from Italian: talent and ability names stay in English, as in the game. Original text (Italian) →
This build takes the Warlock to 60 with damage over time and drains, and from 41 it sacrifices the Felhunter with Demonic Sacrifice: you regenerate health constantly and play without a pet. At the bottom of the Affliction tree Wrack awaits, the new Forever talent that strengthens your other Shadow effects on the target.
How to play it
This build lives on effects that do the work on their own: you apply them, you move, you drain, and meanwhile the enemy wastes away. It heals itself well and has very little downtime, especially from 41, when Demonic Sacrifice makes you regenerate health nonstop and you hardly need to eat anymore. It's at its best against durable enemies; in short fights part of the damage over time goes to waste.
Where the points go
10–13: Suppression. With 4% chance to hit you no longer miss enemies of your level or lower: it's the biggest gain of the early levels, and for leveling it covers all the hit you need.
14–18: Improved Corruption: from 18 Corruption is instant and stronger, and you can cast it on the move.
19–29: one point in Grim Reach, Improved Bane of Agony, Pandemic (doubled crit bonus on damage over time and drains), Nightfall (instant Shadow Bolts from Corruption, drains and Wrack) and three points in Malevolence for more Shadow crits.
30: Siphon Life, another instant effect that heals you and offsets Life Tap.
31–41: eleven points in Demonology, across Demonic Embrace, Demonic Aegis and Fel Vitality, to reach Demonic Sacrifice at 41: by sacrificing the Felhunter you get 3% of your maximum health every 4 seconds for two hours.
42–50: the rest of Malevolence, the second point in Grim Reach (Affliction spell range +20%), the first in Improved Life Tap and Shadow Mastery.
51: Wrack, a 6-second channel that deals damage and meanwhile strengthens your other Shadow effects on the target.
52–60: Improved Life Tap completed (20% more mana from each Life Tap), then Soul Siphon, Improved Drains and Fel Concentration: stronger drains and Wrack, channels that hold up better when you get hit.
For the last eight points, from 53, there's an equally valid alternative: Amplify Curse and Curse of Exhaustion, then Soul Siphon and three points in Fel Concentration, without Improved Drains.
A typical kill
Demon Skin, and from 20 Demon Armor, always active. Before 41, send your pet in first: Voidwalker to hold enemies, Succubus or Incubus for melee damage, Imp at range.
If you like, open from range with Immolate, then the instant effects: Corruption right away; Bane of Agony only on enemies that will live long enough, because it grows over time (don't renew it early); Siphon Life only on enemies that will survive a good part of its 30 seconds.
Spend Nightfall's instant Shadow Bolts between one effect and a channel. Drain Life when you need health, Wrack when you only need damage and your effects are already active. The final blow comes from the wand: no new effects on an almost dead enemy. Life Tap once or twice between casts or while moving, then recover health.
In long fights, pair your Bane with a Curse that lasts: Curse of the Elements, or Curse of Weakness against melee fighters. Drain Soul when you need Soul Shards.
Several enemies at once
Spread Corruption and Bane of Agony, drain one target and move on to new ones as the old ones fall. In dungeons, on packs held by the tank, Rain of Fire or Hellfire.
On gear, spell power and Shadow damage come first, then crit, which pays off more with Pandemic and Malevolence, then Spirit, which increases the mana from each Life Tap; Intellect and Stamina are worth the same.
Strengths
Heals itself and has very little downtime, especially after Demonic Sacrifice.
Damage over time effects hit several enemies at once and tag them instantly.
Much of the damage keeps going while you move.
Excellent sustained damage against durable targets.
Weaknesses
In short fights part of the damage over time goes to waste.
Damage ramps up slowly while you apply your effects.
Keeping track of effects on many targets takes practice.
From 41 you play without a pet: if you summon a demon you lose the Demonic Sacrifice effect.
Notes
Demons: in Forever they come with class quests. Voidwalker at 10, Succubus or Incubus at 20, Felhunter at 30 (Spell Lock with a Grimoire at 36), Felsteed at 40.
Bane and Curse: here Curse of Agony is called Bane of Agony, and you can keep one Bane and one Curse on a target at the same time.
After Demonic Sacrifice, summoning any demon removes the effect: always keep a few Soul Shards to redo it (the Imp doesn't use one). In Forever Soul Shards can drop from Drain Soul ticks even before the enemy dies, and they go in the slot dedicated to the reagent bag.
Health and mana are a single pool: Life Tap, then recover with Drain Life, Siphon Life, bandages, or by eating and drinking together.
Get a wand early: it costs no mana.
Demon trainers sell the Grimoires that teach your demons new abilities. After 41, only buy the utility ones you actually use.
Gather materials while questing to pay for new spell ranks and Grimoires. Log out in rested areas, and offer groups Healthstones, Soulstones and summons.
Race: Gnome for the Alliance (+5% mana). For the Horde the Orc is worth less than usual, because its pet damage bonus is lost when you sacrifice your demon at 41.
