Zardnaar
Legend
I am not 100% sure if this is the best build around in terms of DPR but it is very easy to set up and is playable from level 1. The basic combo is eldritch blast +agonising blast from the warlock class. As worded you get to add your charisma bonus to damage every time eldritch blast hits.
Now unlike the other cantrips EB scaling is an extra attack. You get an extra 1d10 attack as opposed to 2d10 damage. RAW this this means each 1d10 damage deals charisma damage to its target. This is probably RAI as well as the warlock class is really going to stink without it as it I giving up a lot of spells in return for enhanced damage on at will attacks. Unless it can of course abuse the short rest mechanics.
The other interesting aspect of EB scaling is how it interacts with multicasting since if you multiclass heavily you may be giving up multiple attacks. EB only cares about your level not what classes you actually are.
Now this also combos great with the hex spell which is an extra 1d6 damage ecy time you hit a target that can get very abusive with multiple attacks. The downside is the amount of spells the warlock can actually cast as I said the warlock gets gimped in that regard. On the plus side it is a concentration spell that can last for one hour. So we figure out that being good at concentration helps and being able to cast hex a lot is a good idea.
Now this leads one to look at multiclass combinations the sorcerer in particular. The Sorcerer can use their spells to cast warlock spells in their spell slots as well which is sweet potatoes and the Sorcerer is the only spell casting class with proficiency in constitution saves. Put simply start the game as a Dragon sorcerer and multiclass into the warlock at level 2 and take 2 levels to get the eldritch blast+hex combo online. After that you keep taking sorcerer levels.
By level 5 you get an extra attack via eldritch blast and you can have a lot of hex spells to go around Each one deals 1d10+3 damage and if you use hex that is another 1d6 damage on each attacks. By level 5 however you can use twin spell 3 times per day to cast EB twice. That is 4 attacks as a nova dealing 1d10+1d6+3 damage. Hex is also a bonus action to cast and move the hex around. By level 10 you get another attack and you can have 20 charisma as well from 8 levels of sorcerer.
1d10+5+1d6 damage on 3 attacks and 8 times per day you can twin that. That is a lot more attacks than a fighters action surge. You can do it every round for the most part. Speaking of action surge you can add fighter levels as well. For silly levels of nova damage 2 fighter levels will let you action surge as well and you can use twin spell again as well. That is 12d10 damage with +4 or soon each of them +1d6 so your damage is now in the 12d10+12d6+48 damage range at level 10. But only once per day I think I would prefer more sorcerer levels overall.
Now to add more cheese to our fondue however we can get more uses out of EB and cast it more than once per round. This means adding a 3rd warlock level at lower levels and taking a blade pact warlock and creating any weapon with reach. Also be a human at level 1 and take the warcaster feat. You are now proficient at and have advantage on saves to disrupt concentration such as spells like hex. When you use your pact weapon anyone leaving a square within reach provokes an attack of opportunity which means more uses of Eldritch blast via the warcaster feat. You can take a 4th level of warlock at level 5 to get the polearm master feat which lets you get an AoE that can be a spell attack as well or you can take the feat at level 7 with your 4th level of sorcerer and pick up a stat buff at 8 if you want by going 4/4sorcerer/warlock. Note you will never actually use said polearm to make a normal attack you are just using it to trigger AoO with EB. AoO normally allow 1 extra attack, EB allows multiple attacks which combines well with hex.
Now what makes this build actually attractive is that it doesn't suck at low levels and in some ways is actually better than other low level spell casters. Also you do get higher level sorcerer spells as an added bonus. You do get delayed stat bumps/feats but you do not miss out on bonus attacks as such.
Credit goes to Lawolf on the WoTC forums however who spotted a lot of this stuff before I did I have just been tinkering with it and now one of my PCs is going for the basic Warlock+sorcerer build so it is leaving theory crafting and seeing play and her PC is now level 3.
Now unlike the other cantrips EB scaling is an extra attack. You get an extra 1d10 attack as opposed to 2d10 damage. RAW this this means each 1d10 damage deals charisma damage to its target. This is probably RAI as well as the warlock class is really going to stink without it as it I giving up a lot of spells in return for enhanced damage on at will attacks. Unless it can of course abuse the short rest mechanics.
The other interesting aspect of EB scaling is how it interacts with multicasting since if you multiclass heavily you may be giving up multiple attacks. EB only cares about your level not what classes you actually are.
Now this also combos great with the hex spell which is an extra 1d6 damage ecy time you hit a target that can get very abusive with multiple attacks. The downside is the amount of spells the warlock can actually cast as I said the warlock gets gimped in that regard. On the plus side it is a concentration spell that can last for one hour. So we figure out that being good at concentration helps and being able to cast hex a lot is a good idea.
Now this leads one to look at multiclass combinations the sorcerer in particular. The Sorcerer can use their spells to cast warlock spells in their spell slots as well which is sweet potatoes and the Sorcerer is the only spell casting class with proficiency in constitution saves. Put simply start the game as a Dragon sorcerer and multiclass into the warlock at level 2 and take 2 levels to get the eldritch blast+hex combo online. After that you keep taking sorcerer levels.
By level 5 you get an extra attack via eldritch blast and you can have a lot of hex spells to go around Each one deals 1d10+3 damage and if you use hex that is another 1d6 damage on each attacks. By level 5 however you can use twin spell 3 times per day to cast EB twice. That is 4 attacks as a nova dealing 1d10+1d6+3 damage. Hex is also a bonus action to cast and move the hex around. By level 10 you get another attack and you can have 20 charisma as well from 8 levels of sorcerer.
1d10+5+1d6 damage on 3 attacks and 8 times per day you can twin that. That is a lot more attacks than a fighters action surge. You can do it every round for the most part. Speaking of action surge you can add fighter levels as well. For silly levels of nova damage 2 fighter levels will let you action surge as well and you can use twin spell again as well. That is 12d10 damage with +4 or soon each of them +1d6 so your damage is now in the 12d10+12d6+48 damage range at level 10. But only once per day I think I would prefer more sorcerer levels overall.
Now to add more cheese to our fondue however we can get more uses out of EB and cast it more than once per round. This means adding a 3rd warlock level at lower levels and taking a blade pact warlock and creating any weapon with reach. Also be a human at level 1 and take the warcaster feat. You are now proficient at and have advantage on saves to disrupt concentration such as spells like hex. When you use your pact weapon anyone leaving a square within reach provokes an attack of opportunity which means more uses of Eldritch blast via the warcaster feat. You can take a 4th level of warlock at level 5 to get the polearm master feat which lets you get an AoE that can be a spell attack as well or you can take the feat at level 7 with your 4th level of sorcerer and pick up a stat buff at 8 if you want by going 4/4sorcerer/warlock. Note you will never actually use said polearm to make a normal attack you are just using it to trigger AoO with EB. AoO normally allow 1 extra attack, EB allows multiple attacks which combines well with hex.
Now what makes this build actually attractive is that it doesn't suck at low levels and in some ways is actually better than other low level spell casters. Also you do get higher level sorcerer spells as an added bonus. You do get delayed stat bumps/feats but you do not miss out on bonus attacks as such.
Credit goes to Lawolf on the WoTC forums however who spotted a lot of this stuff before I did I have just been tinkering with it and now one of my PCs is going for the basic Warlock+sorcerer build so it is leaving theory crafting and seeing play and her PC is now level 3.