D&D Spell Design

Learn to design combat spells for Dungeons & Dragons. Discover how much damage a Fifth Edition spell should cause at each level.

Chapter VI: Scutwork!, Or, The Wizard’s Apprentice

The wizard’s apprentice, Marleen, blinked at the faded scroll in her hands, drawing it closer to her youthful face. Her mistress was in the throws of creating a new spell and had tasked her with fetching a particular treatise on evocation magic.

Unfortunately, her dominie’s filing system left something to be desired and Marleen had been rummaging through the piles of dusty books and moth eaten scrolls for the better part of an hour.

This must be it though… Yes, here was a section discussing the inverse relationship between a spellcaster’s power’s of concentration and a spell’s raw power. There was a reason, she realized, that absentminded wizards, like her instructress, were often the most formidable.

What Determines A Spell’s Damage?

How are Fifth Edition, Dungeon & Dragons spells designed? In particular, how is a combat spell1 designed? What factors (if any) effect the amount of damage a spell deals?

Interested in discovering how D&D spells that cause damage tick, I looked at 10 different factors I thought might play a roll in determining a spell’s damage:2

  1. A spell’s level.
  2. A spells number of targets.
  3. A spell’s range.
  4. Whether a spell requires concentration.
  5. Whether a spell only deals damage or also has other effects.
  6. Whether the damage occurs on a single or multiple rounds.
  7. Whether a spell requires an attack roll or a saving throw.
  8. Whether a target takes half damage on a successful saving throw.
  9. Whether a spell can be upcast.
  10. Whether the damage is added to a weapon attack.

Initially, I assumed that a spell’s level, number of targets and range would all be important factors. But, what I discovered changed my mind. And, it might surprise you too.

CorrelationDamage per Target
0.04 (negligible)Higher if a spell has a longer range.
0.04 (negligible)Higher if a spell has more targets.
0.23 (negligible)Higher if a spell can be upcast.
0.23 (negligible)Higher if a spell requires a saving throw.
0.30 (low)Higher if a spell only deals damage.
0.39 (low)Higher if a target takes half damage on a successful save.
0.41 (low)Higher if a spell’s damage is not added to a weapon’s damage.
0.41 (low)Higher if a spell’s damage occurs on a single round.
0.49 (low)Higher if a spell does not require concentration.
0.74 (high)Higher if a spell is of a higher level.

Note: Since I included every published combat spell in my investigation, All of these correlations are statistically significant. However that does not mean that they have a significant impact on D&D spell design. In particular, any factor with a negligible correlation can be safely ignored when designing a new 5E spell.

Spell Level

I suspected that a spell’s level would be the most important design factor in a spell’s damage potential.3 On average, this proved to be the case — with two notable exceptions:

  1. On average,4 1st and 2nd level spells deal nearly identical damage. As a result, (when it comes to damage) upcasting a 1st level spell is often a better option than casting a 2nd level spell. In fact, when is comes to single target spells,5 upcasting is often a better choice right through 4th level!
  2. Single target 8th level spells cause less damage, on average, than 7th level spells. In fact, they are only marginally more powerful when it comes to multi-target spells. As we will see later, the main advantage of 8th level damage spells is a major increase in range.

It should also be noted that the variation in the amount of damage caused by spells increases with level. Thus, while the average damage of 1st and 2nd level spells is nearly identical, 2nd level spells have a greater variation in their damage. For example, Scorching Ray does more damage (per target) than almost any 1st level spell (even if that spell is upcast). On the other hand, Magic Weapon, does less damage than any 1st level spell (even when cast with a 1st level spell slot).

Average Damage According To The Dungeon Master’s Guide

How do these results compare to the recommendations found on pages 283-4 of the Dungeon Master’s Guide (DMG)?

Taking the average results indicated by the DMG clearly results in spells that are more powerful than the average spell found in the official publications. (even when we account for the standard deviation at each level). Additionally, the DMG‘s recommendations do not reflect the quirks of 2nd and 8th level spells.

Conclusions

  • Spellcasters would be wise to choose damage spells with other useful effects, or stick with non-damage spells for the 2nd and 8th levels!
  • Aspiring spell designers should be wary of following the DMG’s guidelines too closely, lest they create unintentionally overpowered spells. Moreover, they need to take the exceptions at the 2nd and 8th levels into account if they are interested in creating spells that are in line with the official D&D sourcebooks.

Spell Targets

I hypothesized that the more targets a spell can effect,6 the lower the damage would be for each target. I thought it a reasonable design principle that a spellcaster would sacrifice quality for quantity.7

Surprisingly, there is almost no correlation between a spell’s number of targets and the damage it deals to each target. If anything, spells with more targets tend to deal more damage to each target!8

Damage and Number Of Targets According to the DMG

As the chart below shows, once again, the recommendations found on pages 283-4 of the DMG bears no resemblance to reality.

Conclusions

  • Magic users would be wise to remember that an area of effect spell might do more damage to a single target than a spell that can only target one creature.
  • D&D designers should feel free to follow their hearts, rather than the DMG, when determining a spell’s target to damage ratio.

Spell Range

I supposed that a spell with longer range would be designed to deal less damage. I proposed to myself, that a spellcaster would trade power for distance.

Once again however, there is almost no correlation between a spell’s range and the damage it can deal to each target. If anything, spells with a longer range tend to be more powerful than short range spells!

Conclusions

  • Characters with an arcane bent need not be concerned that a spell’s range might limit its effectiveness.
  • Once again, designers of spells for 5th Edition should feel free to follow their hearts when determining a spell’s range to damage ratio.

Half Damage and the DMG

The DMG indicates that spells that do not deal half damage on a failed saving throw or attack should be 25% more powerful. It is an understatement however, to say that the opposite is true. In fact, spells that deal half damage tend to be significantly more dangerous!

Conclusions

  • Wielders of magic will probably want to rely on spells that do half damage!
  • Magic spell designers have cause to be wary of taking the DMG‘s advice when it comes to half damage!

Spell Concentration

I had thought that a spell’s level, number of targets, and range would be key design factors in determining a spell’s damage. And the DMG suggests that half damage is another important factor in spell design. This turns out not to be the case for two out of the four. So, which of the remaining seven factors also play a significant roll?

After a spell’s level, the second most important factor is whether a spell requires concentration. On average, concentration spells deal less damage than non-concentration spells.

When Does A Spell Require Concentration?

Why do concentration spells do less damage?

As it turns out, concentration is highly correlated with the ability to cause damage on multiple rounds. Thus, a spellcaster is often trading damage amount for damage duration when casting concentration spells.

Also, concentration is often a factor when adding damage to a weapon’s attack (as with a paladin’s smite spells). And, as my first table shows, these spells are correlated with lower damage.

CorrelationConcentration
0 (none)No more likely if a spell has a longer range.
0.09 (negligible)More likely if a spell cannot be upcast.
0.12 (negligible)
More likely if a spell has a fewer targets.
0.22 (negligible)
Less likely if a target takes half damage on a successful save.
0.23 (negligible)More likely if a spell requires an attack roll.
0.24 (negligible)Less likely if a spell only deals damage.
0.26 (low)More likely if a spell is of a higher level.
0.32 (low)More likely if a spell’s damage is added to a weapon’s damage.
0.49 (low)More likely if a spell deals less damage.
0.6 (high)More likely if a spell’s damage occurs on multiple rounds.

Conclusions

  • Casters should be cognizant of the fact that maintaining concentration is vitally important!9
  • Designers should be wary of creating high damage concentration spells (particularly if the damage occurs on multiple rounds) if they are interested in creating spells that are in line with the official D&D sourcebooks.

What Determines A Spell’s Number Of Targets?

As with its damage, the most important factor when determining the number of creatures a spell can target is its level.

CorrelationNumber of Targets
0.01 (negligible)Higher if a spell can be upcast.
0.02 (negligible)Higher if a spell’s damage is not added to a weapon’s damage.
0.04 (negligible)Higher if a spell deals more damage.
0.12 (negligible)Higher if a spell’s damage occurs on a single round.
0.12 (negligible)Higher if a spell does not require concentration.
0.13 (negligible)Higher if a spell only deals damage.
0.23 (negligible)Higher if a spell requires a saving throw.
0.31 (low)Higher if a target takes half damage on a successful save.
0.33 (low)Higher if a spell has a longer range.
0.46 (low)Higher if a spell is of a higher level.

The table below shows how range increases per spell level. Note that I haven’t included the 8th and 9th levels on the chart. The maximum number of targets follows an exponential curve and including these last two levels would have made the rest of the chart difficult to read! However, you can find the last two levels in the table below the chart.

LevelAverage Number of TargetsMaximum Number of Targets
8th1030
9th18.172

Number Of Targets And Total Damage

I also wanted to include the following chart, since it makes clear an interesting tidbit about upcasting. Since the average number of targets increases exponentially, the average total damage of upcast multi-target spells quickly starts to lag far behind multi-target spells cast at their base level.

Conclusions

  • Spellcasting characters should be wary of upcasting a multi-target spell.
  • Spellcrafters would be wise to note the maximum number of targets for each level if they are interested in designing spells that are in line with the official D&D sourcebooks.

What Determines A Spell’s Range?

Interestingly, rather than its level, a spell’s range is most highly correlated with its number of targets.

CorrelationRange
0.01 (negligible)Higher if a spell requires a saving throw.
0.01 (negligible)Higher if a spell only deals damage.
0.02 (negligible)Higher if a spell requires concentration.
0.04 (negligible)Higher if a spell can be upcast.
0.04 (negligible)Higher if a spell deals more damage.
0.09 (negligible)Higher if a spell’s damage occurs on a multiple rounds.
0.11 (negligible)Higher if a spell’s damage is not added to a weapon’s damage.
0.19 (negligible)Higher if a target takes half damage on a successful save.
0.26 (negligible)Higher if a spell is of a higher level.
0.33 (low)Higher if a spell has more targets.

Once again, I haven’t included the average ranges for the spells with the highest number of targets — including them would make the chart impossible to read.

Number of TargetsMinimum RangeAverage RangeMaximum Range
20100437.51000
30158401584015840
32528052805280
72158401584015840

I also include the following chart as it makes clear the maximum ranges that are baked into each spell level.

LevelMinimum RangeAverage RangeMaximum Range
8th601,74215,840
9th602,817.515,840

Conclusions

  • Spellcasters should need to concern themselves with a spells range (except to ensure it is large enough).
  • Those designering spells for 5th Edition, should take both the average range per number of targets and the maximum range per level into account if they are interested in creating spells that are in line with the official D&D sourcebooks.

Final Conclusions

As expected, when is comes to damage, a combat spell’s level is the single most important factor. Unexpectedly however, the second most important factor to account for is concentration.

Additional Reading

Check out these pages for more on designing spells for Dungeons & Dragons 5E.

D&D Next: Spell Design — A look at early 5E spell styles, by Brandes Stoddard (freelance game designer).

How to Make a Homebrew Spell for DnD 5e — Some suggestions on designing spells for 5th Edition D&D, by Jae Carbary (web developer and D&D aficionado).

Notes

  1. I will define a combat spall as a spell that causes damage.
  2. I included every published spell that causes damage in my analysis.
  3. The Dungeon Master’s Guide (DMG) indicates as much in the Spell Damage table on page 248.
  4. I use the mean as my average throughout.
  5. A note on terminology: I am using “target” to indicate any creature damaged by a spell.
  6. I used the Targets in Areas of Effect table on page 249 of the Dungeon Master’s Guide to determine each spell’s number of targets.
  7. This supposition is corroborated by the Dungeon Master’s Guide (DMG) in the Spell Damage table on page 248.
  8. In order to take spell level into account (when determining these averages) I calculated the average for each level (and number of targets) and then averaged those averages.
  9. Not that this really needs reinforcing.

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