Players piloting spellcasters often want to swap out damage types for thematic or mechanical reasons. For example, they might think that a fireball is cooler as an ice explosion. Or, they might want to swap a lightning bolt to fire to keep a troll from regenerating.
In past editions, a spellcaster could accomplish this with Energy Substitution metamagic. Unfortunately, the Transmutation metamagic doesn’t cover every damage type. Also, until recently with the Metamagic Adept feat published in Tasha’s Cauldron of Everything, metamagic was locked into the sorcerer class, unavailable to other spellcasters.
So, it makes sense to dream up a system where characters can swap out damage type. Preferably outside the context of the restrictive metamagic system.
Of course, there are balance considerations. So, instead of making it so that every spell can swap for every damage type (leaving us with a bland slate of forceball, burning force, force bolt, and force strike), we should impose some restrictions. This is good not only for balance reasons–restrictions breed creativity.
So, we’ll divide up all the damage types into classes. I’ve tried to evenly divide them so that the options for swapping are equally numerous. In doing so, I’ve truncated the normal list of “elemental” damage types that you might see in a spell like absorb elements, by moving thunder to positive energy.
Material damage types cause damage like objects in the material plane, such as metal, wood, or stone.
Elemental damage types draw on forces of the elemental planes.
Positive damage types draw on positive energy, which is loud, bright, and shining.
Negative damage types draw on negative energy, which causes decay, disease, and destruction from within.
If you don’t like these classifications, experiment with your own! Let us know in the comments below what works out for you.
Now that we’ve developed a swapping stratification, we need a mechanic to implement it. Something that simulates practicing the magic, leading to later mastery. Since arcana is the skill we normally associate with magic, let’s set an arcana check to see if we can swap the damage type. I’ve opted for an Intelligence (Arcana) check, but you may decide that using a spellcaster’s primary spellcasting score to be a better fit.
Since some spells are more powerful than others, we can impose a scaling DC that keys off the spell’s level. 10 + Spell Level seems like a fair DC to set.
If we succeed, the spell is cast with the new damage type. If we fail, you can either have the spell fail, or you can have it cast with the original damage type.
Since practice can lead to mastery, let’s say that once you’ve swapped a particular damage type on a particular spell three times, you’ve mastered it and can swap freely without worrying about it in the future. You may choose to be more strict and make the player always roll, or you may be more lenient and allow them to freely swap a damage type on other spells once you’ve mastered it with one. Choose the style that seems the best fit for your players and the tone of your campaign. If magic is free and ubiquitous, maybe it’s easier to pull off. If magic is forgotten or rare, perhaps more stringent protocols will achieve that feel.
Here’s my mechanic:
Changing Spell Damage Type
You can change the damage type of a spell. Choose a spell you have cast before. You may try to change the spell’s damage type to another damage type in the same damage class. When you cast the spell, roll an Intelligence (Arcana) check. The DC is equal to 10 + the spell’s level. On a successful roll, you cast the spell using the substituted damage type. On a failed roll, the spell fails.
You master a damage type swap after 3 successes with a specific type. You no longer need to roll to cast the spell with the substituted damage type.
For spells with multiple damage types, you can only swap one damage type that you have not mastered casting.
You can snag a PDF of these rules on the ThinkDM Patreon, where we’ve also leveraged Damage Class for other interesting spellcasting tricks! Today’s cover image is Mind’s Desire by Anthony Francisco, used under the Wizards Fan Content Policy.