Here we look at the cantrip eldritch blast, which exists only on the warlock spell list and is widely accepted as one of the best, if not the best, damage cantrip in D&D right now. As always, I’ll be breaking it down into the basic rules of the cantrip itself, then expanding into potential optimisations to really squeeze the most from this spell.
If we take a look at the Standard Reference Document, we see that the rules of eldritch blast are as follows:
Eldritch Blast 5e
Casting Time: 1 action
Range: 120 feet
Components: V, S
A beam of crackling energy streaks toward a creature within range. Make a ranged spell attack against the target. On a hit, the target takes 1d10 force damage.
The spell creates more than one beam when you reach higher levels: two beams at 5th level, three beams at 11th level, and four beams at 17th level. You can direct the beams at the same target or at different ones. Make a separate attack roll for each beam.
Looking simply at the rules, this cantrip follows the general similarities between most damage cantrips. It takes an Action to cast, it requires only Verbal (V) and Somatic (S) components, it has an Instantaneous duration, and it takes the form of a spell attack roll.
Spell attack rolls are always calculated as the total of your spellcasting modifier (which will most likely, but not always be Charisma, given that this is a Warlock cantrip) + your proficiency bonus.
Why Eldritch Blast is Unique
This spell breaks the mold somewhat in how it scales with level. All damage cantrips scale at 5th, 11th, and 17th levels, but this usually takes the form of an extra damage die. For example, up until 5th level, eldritch blast is indistinguishable from fire bolt, with the all the same rules, except that fire bolt does fire damage instead of force damage, and it sets flammable things ablaze.
However, eldritch blast is unique in that instead of adding another die, the caster instead gets to make another attack roll.
While this might not seem like a huge difference given that it will do the same damage as a single attack cantrip if all attacks are made against the same target, the real game-changer is that it can attack multiple targets, as well as the fact that because the caster gets to make multiple spell attacks, they have a higher chance to land a critical hit and increase their damage further.
In terms of getting access to this cantrip, you have a few options, the most obvious being to play or multiclass into the Warlock class. The Magic Initiate and Spell Sniper feats would also allow any class to pick up this cantrip, but given the specific spell list restrictions of those feats, Charisma will always be the spellcasting modifier you have to use when casting it.
How to Optimise Eldritch Blast
Given the fact that this cantrip allows the caster to make more spell attacks, it does actually scale similar to a Fighter’s Extra Attack feature, eventually granting four attacks at level 17, which is a whole 3 levels sooner than the Fighter gets it.
It also has the second-best damage die with a d10, and it deals objectively the best damage type in the game, force damage, because it is the damage type that the fewest creatures have resistance to or immunity against. Despite these things, it is only marginally better on its own than some of the other good damage options, such as fire bolt and toll the dead.
This cantrip really becomes strong when it is taken on a Warlock and combined with the Agonizing Blast Eldritch Invocation (available from the 2nd level of Warlock), which allows the caster to add their Charisma modifier to the damage the spell deals on a hit. Assuming a maximum Charisma of 20, this means you’ll be adding +5 force damage to each beam that hits, for a maximum of +20 damage assuming you can cast and hit with all four beams.
Eldritch Invocation Options
This extra damage is not all that Eldritch Invocations can offer, as there are a number of others that can also boost the utility of eldritch blast:
Repelling Blast – When you hit a creature, you can push it up to 10 feet away from you in a straight line. There is no limit on this in terms of the size of the creature or how many times you can use it per turn, nor does the target get any sort of saving throw to resist the effect. Enjoy shunting anything up to and including an Ancient Dragon 40 feet per turn.
Lance of Lethargy – Once per turn, you can reduce the speed of a creature you hit by 10 feet. Not quite as insane as Repelling Blast, but this also has no save, and if the two are stacked, then assuming the creature hit has a movement speed of 40 or less, they will never be able to reach you in melee. Nasty!
Grasp of Hadar – Once per turn, you can move a creature 10 feet closer to you in a straight line. Like Repelling Blast, but pulls them closer and only once per turn. Given that you are committed to ranged combat (why else are you using eldritch blast?), this is a more niche option, as you’ll most likely want enemies further away from you, not closer, and considering it’s also limited to once per turn. Still, if you enjoy shuffling your opponents around the board like chess pieces, then this might be a good pick.
Eldritch Spear – The range of eldritch blast is increased to 300 feet. More than doubling the initial range of 120 feet, this is useful if your target is way over in the distance or perhaps if you are flying a considerable height above them.
This cantrip can be optimized further, but that will have to wait for the article on the hex spell, and finally in the Sorlock (Sorcerer + Warlock) multiclass build guide.