The fiend pact is the way to go. As another person wrote, hex, relentless hex, agonizing blast, and pretty much whatever other eb related invocs you want. If you manage to get the last kills you get temp hp, with for lv 8 4 cha would be 12 health per kill. I plan on using by persuasion check against the DM to see if he'll allow me to use the illusionists bracers. They would take eldritch blast to a new level. And eventually, you'd deal 8 d10, + 8 d6 + 40 and could use that fiend ability to knock on another 10 d10 on the targets next turn. Sounds like an insanely satisfying kill. Eldritch spear will let you do that from 300 ft, spell sniper I think takes that up to 600. You're now a better archer than a ranger could ever hope to be, and I found a cute little homebrew feat that's basically war caster minus the part about having both hands full, but it adds that ranged spell attacked aren't at disadvantage at 5ft so... Now you've become a rangers wet dream, and if the fighter doesn't take great weapon master/sharpshooter, you're better at it than them too. Plus that whole casting eb twice a turn doesn't use up any abilities, so it's superior to action surge in this application. Ok well... Now if you took 2 levels into fighter.... You could fire off 3 eldritch blasts a turn, another on as an opportunity attack too, if it gets provoked
Agonising blast is non negotiable. Hex is S tier too.
Hex blades curse, a subclass feature from the hex blade patron stacks well here too.
An upgrade from hex is bestow curse, though that's difficult to acquire.
I think the quickened spell Metamagic option which can come from either the Metamagic feat or 3 levels in sorcerer should not be overlooked here. It allows an additional cast of eldritch blast on each of your turns at the cost of your bonus action. Providing you have the Metamagic points to burn.
Another interaction I feel has a lot of potential is the 6th level feature of the wizard| Bladesinger "extra attack" feature. However, the bladesinger's extra attack allows you to forgo one of your weapon attacks when you take the attack action, in order to cast a cantrip as part of that attack action. Crossbow expert feat will be required for those melee range eldritch blasts to not be made with disadvantage.
Bonus Min maxing interaction. You can pick up eldritch Smite and apply those off your weapon attacks.
A 2 level dip in fighter for action surge.
Combine all of this and you can:
Take the attack action on your turn, attacking twice. First attack is with your pact/hex weapon. Apply eldritch Smite.
Forgo your second attack as part of that attack action to cast a cantrip. Cast eldritch blast.
Bonus action: quickened spell an eldritch blast.
Action surge to gain an additional action. Spend action to cast a spell: eldritch blast. If the target/s were affected by hex (possible with the twinned spell Metamagic) or hex blades curse, or bestow curse, the damage is pretty crazy
The 14th level ability hurl through hell will add a 10d10 attack onto one attack that hits per long rest. Not sure that is better than a consistent proficiency bonus one one attack every round or the hexblades curse of proficiency bonus on every attack for a minute. And they also get temp HP on a kill giving a bit more versatility. It is overall a very solid choice for it, whether its the best im not sure. Either genie or hexblade will get you more sustained damage, but burst damage has its perks.
Once per turn, you can deal an extra 2d6 damage to one creature you hit with an spell attack if you have advantage on the attack roll. You don’t need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn’t incapacitated, and you don’t have disadvantage on the attack roll.
Adding that feat as well might help if you either get advantage or foes adjacent to each other
Where is surprise spellcasting from? Looks fun but I'm not seeing it anywhere
Once per turn, you can deal an extra 2d6 damage to one creature you hit with an spell attack if you have advantage on the attack roll. You don’t need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn’t incapacitated, and you don’t have disadvantage on the attack roll.
Adding that feat as well might help if you either get advantage or foes adjacent to each other
Where is surprise spellcasting from? Looks fun but I'm not seeing it anywhere
17 levels in warlock, 3 in sorcerer for metamagic, Add a few feats to boost Damage and range...
The fiend pact is the way to go. As another person wrote, hex, relentless hex, agonizing blast, and pretty much whatever other eb related invocs you want. If you manage to get the last kills you get temp hp, with for lv 8 4 cha would be 12 health per kill. I plan on using by persuasion check against the DM to see if he'll allow me to use the illusionists bracers. They would take eldritch blast to a new level. And eventually, you'd deal 8 d10, + 8 d6 + 40 and could use that fiend ability to knock on another 10 d10 on the targets next turn. Sounds like an insanely satisfying kill. Eldritch spear will let you do that from 300 ft, spell sniper I think takes that up to 600. You're now a better archer than a ranger could ever hope to be, and I found a cute little homebrew feat that's basically war caster minus the part about having both hands full, but it adds that ranged spell attacked aren't at disadvantage at 5ft so... Now you've become a rangers wet dream, and if the fighter doesn't take great weapon master/sharpshooter, you're better at it than them too. Plus that whole casting eb twice a turn doesn't use up any abilities, so it's superior to action surge in this application. Ok well... Now if you took 2 levels into fighter.... You could fire off 3 eldritch blasts a turn, another on as an opportunity attack too, if it gets provoked
may i ask why the fiend?
Agonising blast is non negotiable. Hex is S tier too.
Hex blades curse, a subclass feature from the hex blade patron stacks well here too.
An upgrade from hex is bestow curse, though that's difficult to acquire.
I think the quickened spell Metamagic option which can come from either the Metamagic feat or 3 levels in sorcerer should not be overlooked here. It allows an additional cast of eldritch blast on each of your turns at the cost of your bonus action. Providing you have the Metamagic points to burn.
Another interaction I feel has a lot of potential is the 6th level feature of the wizard| Bladesinger "extra attack" feature. However, the bladesinger's extra attack allows you to forgo one of your weapon attacks when you take the attack action, in order to cast a cantrip as part of that attack action. Crossbow expert feat will be required for those melee range eldritch blasts to not be made with disadvantage.
Bonus Min maxing interaction. You can pick up eldritch Smite and apply those off your weapon attacks.
A 2 level dip in fighter for action surge.
Combine all of this and you can:
Take the attack action on your turn, attacking twice. First attack is with your pact/hex weapon. Apply eldritch Smite.
Forgo your second attack as part of that attack action to cast a cantrip. Cast eldritch blast.
Bonus action: quickened spell an eldritch blast.
Action surge to gain an additional action. Spend action to cast a spell: eldritch blast. If the target/s were affected by hex (possible with the twinned spell Metamagic) or hex blades curse, or bestow curse, the damage is pretty crazy
The 14th level ability hurl through hell will add a 10d10 attack onto one attack that hits per long rest. Not sure that is better than a consistent proficiency bonus one one attack every round or the hexblades curse of proficiency bonus on every attack for a minute. And they also get temp HP on a kill giving a bit more versatility. It is overall a very solid choice for it, whether its the best im not sure. Either genie or hexblade will get you more sustained damage, but burst damage has its perks.
I suppose in order to min max eldritch blast better we'd need to weigh up the benefits and costs of multiclassing
Where is surprise spellcasting from? Looks fun but I'm not seeing it anywhere
It is a Home Brew feat.
Undead warlock makes it 2d10 per blast.
Fathomless Warlock. Combination of EB, Hex and Tentacle of the Deeps.
EB x 2
Agonizing Blast + 4 (or 5) dam CHA
Tentacle of the Deeps + d8 dam. Also slow 10 ft.
Hex + 1d6 per attack that hits.
Lance of Lethargy. Slow 10 ft.
Repellant Blast. 10 ft per move hit.
Assuming all hit - Total: 2d10 + 8 + d8 + 3d6 + 20ft slow + 20 ft push back.
The downside is Hex requires a bonus action to set up and TotD a bonus action to set up and to use.
If you include magic items - Illusionist's Bracers might be even better.