My take for the moment (been working on it for less than an hour; gotta finish the druid first)
1: Eldritch Blast, Hex (Cha/long rest), Patron (1 new patron feature to replace Bonus Spell)
2: Invocation (2)
3: Boon
4: ASI
5: Hex (Cha/short rest)
6: Patron feature
7: Eldritch Emissary: 2 language, advantage on Cha check against Fiend, Celestial and Fey
Shadow Walk: AoO against you have disadvantage. Can hide in Dim light.
8: ASI
9: Nightmare Ritualist: Cast Commune, Contact other plane or Dream for free as ritual after a long rest (ala dream druid)
10: Patron feature
11: Unspeakable bond: As a reaction when damaged, transfer damage to a willing ally within 15'. Ally has advantage on next roll until the end of its next turn.
12: ASI
13: Perilous Bargain (1/use): Next roll is a nat 20, but Vulnerable to damage until start of next turn. 1/ Long rest.
14: Patron feature
15: Greater Hex: You can Hex as a reaction enemies that attack you.
16: ASI
17: Summon Patron (1/week Planar Ally for free)
18: Perilous Bargain (2 uses)
19: ASI
20: Patron feature
Invocations:
lvl 2: 2
3: 3
4: 4
5: 5
6: 5
7: 6
8: 7
9: 7
10: 8
11: 9
12: 9
13: 10
14: 11
15: 11
16: 12
17: 13
18: 13
19: 14
20: 15
New Invocations
Beshadowed Blast (Requires Eldritch Blast, Warlock level 9)
Once per turn, one creature hit by a blast is unable to see beyond 15 feet away until the start of your next turn.
Breath of Night (Requires Warlock level 5)
You can cast Fog Cloud at-will.
Brimstone Blast (Requires Eldritch Blast)
You can change the force damage from your Eldritch Blast to fire damage. If you do so, the damage increases to 2d6.
Eldritch Chain (Requires Eldritch Blast, Warlock level 7)
When you roll a critical hit with Eldritch Blast, you can deal the spell damage to another creature within 15 feet of the initial target.
Eldritch Line (Require Eldritch Blast, Warlock level 9)
As an action, a line 30 feet long and 10 feet wide blasts out from you in a direction you choose. Each creature in the line must make a Dexterity saving throw. A creature takes 2d10 force damage on a failed save, or half as much damage on a successful one.
Eldritch Doom (Requires Eldritch Blast, Warlock level 15)
As an action, you can cast Eldritch Blast targeting all creatures in a 10 feet radius sphere within 60 feet. All creatures in the sphere must succeed at a Dexterity saving throw or take 4d10 force damage.
Flee the Scene (Requires Warlock level 7)
You can cast Mislead and Misty Step as part of the same action once per long rest without expending a spell slot.
Hellrime Blast (Requires Eldritch Blast)
Your Eldritch Blast deals cold damage instead of force damage. Once per turn, one creature hit by a blast can't take reactions until the start of its next turn.
Hideous Blow (Requires Eldritch Blast)
You can cast Eldritch Blast as a melee spell attack.
Ignore the Pyre (Requires Warlock level 7)
As an action, you can grant yourself resistance to Fire, Cold, Acid or Necrotic damage until your next rest. Once you use this feature, you can't use it again until you take a short rest.
Miasmic Cloud (Requires Warlock level 15)
You can cast Cloudkill and Stinking Cloud as part of the same action without using a spellslot. You are considered as concentrating on both of them at the same time and a failed concentration check loses both spells. You cannot use this feature again until you take a long rest.