Skill Gem Setup
Act 1 Setup:

Contagion + Unleash - Multitarget spreading.
Unearth + Prolonged Duration - Summons scorpions to Path of Exile 2 Currency extend contagion chains.
Essence Drain + Chain - Main DoT and clear combo.
Chaos Bolt + Rapid Casting - Stack Wither debuff on bosses.

Act 2+ Setup:

Despair (Cursed Ground or Heightened Curse) - Amplify Chaos damage taken.
Dark Effigy + Controlled Destruction - Boosts DoT damage during boss fights.
Sigil of Power - Precast before encounters for amplified damage and mana sustain.
Convalescence + Rapid Casting II - Emergency defensive utility.

Tip: You can use Flame Wall at levels 2-5 for early single-target support until Essence Drain is unlocked.

Passive Tree & Ascendancy

Start by picking Eldritch Empowerment for raw Chaos damage scaling, followed by Soulless Form for mana sustain. Once you've acquired at least three Chaos clusters, respec the Witch's starting Intelligence nodes for optimized efficiency.

Permanent Buff Recommendations:

Valley of the Titans Medallion: +30% Charm Charges
Venom Crypts Poison Vial: +30% Stun or Ailment Threshold
Orbala's Pillar: +3% Movement Speed
Goddess of Justice: +30% Flask Mana Recovery

How the Build Plays

Clearing:

Open fights by casting Contagion on a low-health target, then follow up with Unearth to summon scorpions that spread the debuff. Once Essence Drain is available, alternate between the two - cast Contagion first, then Essence Drain for guaranteed spread.

Single Target:

Against bosses, lead with Sigil of Power and Dark Effigy. Apply Despair, cast Essence Drain, then stack Chaos Bolt to amplify wither debuffs. Refresh Essence Drain before expiration for maximum uptime.

Conclusion

The Path of Exile 2 Witch Chaos Spell Leveling Build offers a perfect blend of simplicity and power. It clears packs effortlessly with Contagion and Essence Drain, handles bosses efficiently with Chaos Bolt and Despair, and requires minimal investment - ideal for league starters or self-found players.

With consistent gear upgrades, proper rune management, and careful flask usage, this Witch will carry you to mapping content faster than most archetypes. For those seeking to maximize early-game efficiency, chaos magic remains one of cheap POE 2 Divine Orbs the most reliable - and satisfying - ways to dominate Wraeclast's darkest corners.