What is the most damage one can do with a cantrip in one turn?

I'm curious as to what the maximum damage you could potentially do with a single cantrip is.

So far the most I can think of is a Warlock of at least two levels with the Eldritch Blast cantrip and the agonizing blast invocation and a 20 in CHA with a total character level of 17 or higher for 4 beams against a target afflicted by Hex and Hexblade's Curse. Which is a total of 1d10+1d6+8 per beam for a grand total of 96 maximum damage (4d10+4d6+32). Beyond that however, I can't think of anything.

Stipulations:

• Preferably contain all setup and the casting of the cantrip in the same turn but if necessary you may have one turn to prepare.
• The damage MUST be done by the cantrip but spells like Hex that don't directly deal damage are ok.
• Don't factor in resistance or vulnerability.
• Since we're talking theoretical maximum damage you can assume any damage dice rolled to have their highest value and that all attacks hit but do not crit.
• You can assume advantage on your attack rolls for the purposes of pricing abilities like the rogue's Sneak Attack.
• The damage must all be from the same source so for example you can't use Grasp of Hadar and Repelling Blast to move the target back and forth through a Wall of Fire or to push the target off of a cliff.
• This is single target damage only.
• This is for a single character by himself with no magic items for him or the target now nor in the past
• @Medix2 If you can guarantee a crit following the other stipulations go for it Oct 2, 2019 at 22:19
• @Medix2 Sure, you can assume advantage for the purposes of proc'ing skills like sneak attack. Assume whatever you like for the wild magic surges. You can shapechange to get higher than 20 if you're able. Also I'm thinking single target damage. Oct 2, 2019 at 23:05
• Does damage from forced movement (say, repelling blast into a wall of fire or whatnot) count as damage done by a cantrip? My current answer is Wiz 17/Sorc1/War2, and it relies on Grasp of Hadar/Repelling Blasting a target back and forth through an allowed-to-do-damage-multiple-times-per-turn lethal zone. Oct 2, 2019 at 23:14
• @Himitsu_no_Yami: Eldritch Smite is a warlock invocation, not a spell (and Divine Smite is a paladin class feature) - but there are 7 smite spells. They do indeed do extra damage on the same attack, plus an additional effect.
– V2Blast
Oct 3, 2019 at 0:04
• @Ruse Yes, I mentioned this before but it looks to have been removed. No forced vulnerability either. Someone brought up the Grave Domain Cleric but deleted their comment Oct 3, 2019 at 16:06

The requirements:

We will need a Half-Orc Warlock (11) / Paladin (2) / Assassin Rogue (7).

These get us Savage Attacks, branding smite, Hexblade's curse, the Eldritch Smite Invocation, Divine Smite, Sneak Attack, and Assassinate. On top of this we need the Martial Adept feat and the Orcish Fury feat, and we will select the Dueling Fighting Style from Paladin. We will be using the booming blade cantrip.

On our turn:

On our turn we cast branding smite as a fifth level spell (5d6) onto our rapier (1d8). We cast booming blade making an attack (3d8), proc-ing Sneak Attack (4d6) as well as Divine Smite using a fifth level spell slot (5d8) and Eldritch Smite using a fifth level spell slot (5d8). We also use a maneuver gained through the Martial Adept feat (1d6), the Half-Orc's Savage Attacks (1d8), and the Orcish Fury feat (1d8).
All of these dice rolls (except Savage Attacks) are doubled due to the Assassinate feature.

Then we have the static modifiers: Our ability score modifier (5) and the Dueling Fighting Style (2).

Putting these together we have the following damage:
$$8 + 5 + 2 + 2\times(30+8+24+24+40+40+6+8) = 15 + 2\times(180) = 375\text{ damage}$$

Note that this does not use hex nor Hexblade's Curse as these require bonus actions, and that is being spent on branding smite.

• You could probably eke out a bit more damage with proper magical item selection on the rapier. If you can somehow swing a bit of fire damage on the rapier as part of that, then going with the Celestial Warlock would let you add your charisma again. Oct 4, 2019 at 1:41
• And with a setup round, Hex and something else could probably add to that. Jan 15, 2021 at 9:38

355 damage, or 467 with setup

The character

• Half-Orc for Savage Attacks
• 2 Fighter levels for Action Surge
• 2 Paladin levels for Divine Smite, searing smite, and 1 caster level
• 2 Divination Wizard levels for booming blade, absorb elements, Portent, and 2 caster levels
• 14 Forge Cleric levels for Blessing of the Forge, bestow curse, 3 ASI (Great Weapon Master, Martial Adept, Orcish Fury), Divine Strike, and 14 caster levels
• The total caster level is 17, so the Half-Orc has a 9th level spellslot
• Notable ability scores: 18 strength, 13 intelligence, 13 wisdom, 13 charisma

The turns

The order of operation isn't super strict but this is what you do:

Optional setup turn:

• Light a torch and inflict fire damage upon yourself
• Cast an 8th level absorb elements
• Use Action Surge
• Cast 5th level bestow curse chosing the last option

Damage turn:

• Cast 9th level searing smite
• Use Great Weapon Master
• Use Portent to foresee a critical hit
• Use Orcish Fury
• Use Divine Smite with a 5th level spellslot
• Use Divine Strike
• Use a maneuver from Martial Adept, such as Pushing Attack
• Use Savage Attacks

The calculation

Curly brackets enclose damage derived by the optional setup turn.

portent × (greataxe + orcish_fury + searing_smite + booming_blade + divine_smite + divine_strike + pushing_attack {+ bestow curse + absorb_elements}) + blessing_of_the_forge + strength_modifier + great_weapon_master + savage_attacks

= 2 × (1d12 + 1d12 + 9d6 + 3d8 + 5d8 + 2d8 + 1d6 {+ 1d8 + 8d6}) + 1 + 4 + 10 + 1d12

= 355 {+ 112} damage with maximized damage rolls.
= 207.5 {+ 65} damage with average damage rolls.

• You could replace rogue with basically anything else (but need an ASI) and use GWM feat and a harder hitting weapon such as 1d12. I think that ends up doing more than sneak attack. Also I think you can cast bestow curse on the first turn, just regularly. Oct 3, 2019 at 3:18
• @Medix2 I need to take damage for absorb elements during the setup turn, but I can't think of a way to do so without using my action, other than quickened spell, but as you pointed out earlier casting as a bonus action messes with my ability to cast as a reaction on the same turn. You may be right about the d12, I'll look into it.
– Ruse
Oct 3, 2019 at 6:15
• Does Savage Attacks double on a crit? Oct 3, 2019 at 12:59
• Also note that without a setup turn there's no reason to have two fighter levels. So you could put them towards something else. Honestly at this point in debating just making a table of ways to gain damage and mathematically proving the maximum Oct 3, 2019 at 13:17
• So... you're expecting that you get lucky enough on your portent rolls that you happen to have a 20 on hand today? Oct 4, 2019 at 1:43

212 damage, or 260 with setup

The character

• Bugbear for Surprise Attack
• 9 Hexblade levels for eldritch blast, hex, Agonizing Blast, Hexblade's Curse, Sign of Ill Omen (grants bestow curse), and 5th level spell slots
• 3 Assassin levels for Assassinate
• 3 Sorcerer levels for Subtle Spell
• 2 Fighter levels for Action Surge
• Notable ability scores: 13 dexterity, 20 charisma

The turns

The order of operation isn't strict but this is what you do:

• Optional setup "turn":
• Cast hex on the target using the Subtle Spell Metamagic. This happens outside of combat, while we are hidden.
• Initiate combat by surprising your target and roll a higher initiative than them so that Assassinate and Surprise Attack apply.
• Damage turn:
• Cast bestow curse on your target choosing the last benefit. As a 5th level spell it does not require concentration.
• Place the Hexblade's Curse on the target
• Use the Action Surge to cast eldritch blast at the target

The calculation

Curly brackets enclose damage derived by the optional setup.

[# of beams] × ([assassinate] × ([eldritch blast] + [bestow curse] {+ hex}) + [agonizing blast] + [hexblade's curse]) + [assassinate] × [surprise attack] = 4 × (2 × (1d10 + 1d8 {+ 1d6}) + 5 + 6) + 2 × 2d6

= 212 {+ 48} damage with maximized damage rolls.

= 138 {+ 28} damage with average damage rolls.

• I'm unsure about the sentence "Cast hex on the target using the Subtle Spell Metamagic. This happens outside of combat because there is no perceivable effect." it seems odd at the very least Oct 3, 2019 at 0:05
• @Medix2 It's worded so that it can happen outside of combat so the target can still be surprised. Hex doesn't have a perceivable effect so as long as the target doesn't notice you (ie you pass a stealth check) it doesn't initiate combat. Subtle Spell removes the need for that check. Oct 3, 2019 at 0:09
• Hex has a material component, which is not removed by Subtle Spell. (And per XGtE's clarification of the PHB rules on spell components (p. 85): "The form of a material component doesn’t matter for the purposes of perception, whether it’s an object specified in the spell’s description, a component pouch, or a spellcasting focus.") Hex's casting is visually perceptible.
– V2Blast
Oct 3, 2019 at 0:17
• @Ruse: It's perceptible as a component of spellcasting, is the point I'm making. Whether you think that's enough to start combat is up to you; I'm just saying the existing claim that "there's no perceivable effect" is wrong (...well, technically the casting of the spell is distinct from the spell's effect, but yeah).
– V2Blast
Oct 3, 2019 at 0:45
• That's the rule, whether it's the norm or not is neither here nor there. 5e simplified a lot at the expense of logic. Oct 3, 2019 at 11:59