For a specific leveling guide, follow this video: https://youtu.be/w2wk1XwaQ2w
This Build is a fantastic starter as well, that can progress to my version of a Bleed Warlock, or into any Warlock Build you want to try. It takes you right up to level 55 at the end of the Campaign, and has a seamless transition into the rest of my follow-up Build Videos to take you to Level 100 and up to 1000+ Corruption. The best part, the Life Variation only needs a few unqiues and no LP!
Levels 1-17
We start out with a basic opener of Forbidden Knowledge 8/8, Stolen Vitality 8/8, and Blood Aura 4/8 to get us to our 20 required to unlock Warlock at 17.
For skills we use Rip Blood, Bone Curse, Wandering Spirits, Summon Bone Golem, and Summon Skeleton. Our goal is to cast Bone Curse, and them spam Rip Blood to procs, using our minions to give us free attack triggers for Bone Curse.
Specialize Splatter 5/5 in Rip Blood for AOE clear and triggers of Bone Curse. Also go with Defile Defenses 5/5 in Bone Curse for easy early damage.
Levels 17-35
To make this transition easier, focus on your Rune of Ascendance first on wands for Mad Alchemist's Ladle, next focus on armor for Exsanguinous.
From here we should have unlocked Warlock! We focus on rushing for Soul Stealer 5/8 and Occultist's Mind 5/8 for as much Mana Regeneration and sustain as possible. This build is VERY mana hungry, this should be our top priority! Next get to Lich for Apocrypha 5/10, and then move back to Warlock to work toward Cauldron of Blood 5/8 and Unholy Torment 6/6 for easy early damage.
We drop Wandering Spirits. Rip Blood and Summon Skeleton for Spirit Plague, Chthonic Fissure, and Chaos Bolts. Our main combo is now online with us dropping a Fissure and them Spirit Plague for constant damage, and Chaos Bolts for single target focus.
Drop Rip Blood and Bone Curse Specializations to instead go with Stygian Current 5/5 in Fissure, and Devour the Damned 1/2 & Cursed Blood 1/1 in Chaos Bolts for sustain.
Levels 35-55
Follow the recorded tree and skill specializations here: https://www.lastepochtools.com/planner/om630M8A
This will bring you up to the point of the last transition at approximately 52-55 for killing the campaign boss and moving into Monoliths.
Our only real big change here in 35-55 is adding back Defile Defenses 5/5 with Bone Curse as our 4th Specialization until we unlock Profane Veil.
Levels 55+
From here transition into the standard tree listed in this build if you have the gear, and try to focus on the preferred gear/affixes listed in the guide.
The biggest thing is being patient and letting the build carry you into about 100-200+ Corruption with just the gear you find. Don't worry about making an early transition to low-life until you find PrefixExperimental Ward per Missing Health & Exsanguinous. Once you have at least a 12%+ Ward affix, make the transition to low-life, as this is the stronger way to play this build in the long term.
Until then, look above at my Life Variation to show you some suggested gear options.