Profane Wand - will be your best in slot thanks to the cast speed implicit. There are 2 options to the wand based on your budget. If you don't have currency for the trigger mod, just use arcanist brand linked with the gems in the wand and socket them into your boots/gloves/helmet, whatever.
For the trigger craft version, I fractured it myself, then I used chaos orbs until I hit the +1 all spell mod, crafted a 3rd prefix, and made sure I had 2 suffixes, then i bench crafted "Cannot Roll Attack Mods" and used the harvest "Augment chaos mod" this will guarantee +1 chaos spell skill gems mod, once your prefixes are done, lock them and use reforge caster to get either spell crit, or cast speed. Once you get either one of those, lock prefixes again and use again "augment caster" that will guarantee your other required mod. For the 3rd prefix, bench craft crit multi or if you're feeling risky, you can Foulborn Exalt it on the boat or veiled exalt it, in hopes you get crit multi, or a version of crit multi.
Lich's Circlet is your best in slot helmet, if the double influenced helmet with +1 power charge and nearby enemies have -#% chaos res, then just focus on getting a very high ES helmet, and for the suffixes, INT, Fire Res, or Aspect Arakaali, or rarity. I just bought the helmet because I got no idea how to use recombinators.
Dawnbreaker will be mandatory with a MAX roll on the Phys taken as fire. The other rolls are not that relevant, since you can balance it out with your watchers eye.
Shavronne's Revelation is a fantastic ring here, giving us almost 300 flat energy shield once socketed into your left ring slot. Try to get a +1 power charge corruption if you have the currency for it.
Nimis will be your best in slot for the 2nd slot, basically giving us double damage with the return projectile without any damage penalties.
Mageblood is the best belt, fixing a lot of issues
Replica Dragonfang with +3 soulrend is the best budget option. Try to get 5% chance to block attack damage corruption implicit. For the more expensive version, a +1 all +1 chaos 
Croaker Talisman is slightly better. Get or fracture +1 all skill gems, reforge caster until you hit good Spell damage prefix, make sure you have 2 suffixes, then bench craft "cannot roll attack mods" and havest augment chaos mod, this will guarantee you a +1 chaos spells, if you're lucky to keep the spell damage prefix, then move to the suffixes, lock prefixes, reforge caster/crit to get cast speed and crit multi, once you have either of those, lock prefixes again, and augment caster/crit in hopes to get whatever you are needing. If it removes a bad mod, start over from the previous step.
Cloak of Flame will be the best in slot here, try to get a corrupted one with +1 socketed gems, or if you're really rich, get a +1 socketed gems and a +2 projectile gems
Warlock Gloves - Temple mod with 50% increased damage against chilled enemies is a must, because we always chill enemies thanks to Stormblood Sapphire Flask. For the prefixes focus on high ES, and for the suffixes, Fire Res/ INT/ and the best in slot suffix would be 50% cast speed while focused.
To craft these, first either fracture or buy the fractured temple mod, spam essences of WOE until you hit prefixes you are happy with, eldritch currency craft the suffixes until you hit INT, then lock prefixes, use a Veiled Exalted Orb on the boat, and hope it removes the crafted mod, and you unveil cast speed. If you don't unveil that, rinse and repeat.
Warlock Boots - These will give us our ailment immunity, get a fractured ES base, spam essences of torment until you get good suffixes, then finish prefixes with eldritch currency / boat crafting.
Stormblood Sapphire Flask - this will guarantee all hits will apply chill.
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For use to be able to use all our auras, we need to do some shenanigans.
Forbidden Flesh and Flame combo for Guardian, will give us great mana reservation efficiency, and a nice 10% spell block.
Stormshroud combined with our boots will give us ailment immunity.
Transcendent Flesh positioned next to the Scion starting zone, will give us almost 200% critical strike multiplier. since 
Soulrend of Reaping cannot benefit from multiple crit multi jewels, this is a great way to get some extra crit multi.
Watchers eye with 
Purity of Fire mod and 
Clarity mod, that gives us max mana as extra max energy shield.
Impossible Escape Supreme Ego, will allow us to snatch 
Charisma and another small reservation passive.
Now just that won't allow us to get enough mana to cast everything and still cast our spells. Try to get as many corrupted rare jewels with 2% increased mana reservation efficiency of skills implicit. Focus on getting these mods:
- Increased max ES
- Spell crit multi
- Cast speed
- Cast speed while holding a shield
- 1 max fire res roll
- % increased spell damage
Lethal Pride (Rakiata Tempered by War) - try to get 2 or 3x double damage
Scion
Reliquarian
Arctic Armour, making us take 22% LESS fire damage taken while stationary, and while bossing, you're mostly stationary to be able to cast. 
Frost Shield and 
Sigil of Power in the mix, and you got yourself a real thick tank. 
Snakepit until you have the currency for 
