For example, I want an Aasimar with fire resistance instead of radiant resistance. Is there a way for a subrace to get rid of the resistance of the base aasimar?
No, but there is a way for a Variant Race to do it. Make a “Granted” trait for the Variant race and under the dropdown labeled “REPLACE BASE RACE RACIAL TRAIT” choose “Celestial Resistance.” That will cause whatever you make for your homebrew variant racial trait to replace the whole base trait (so if you intend to keep the Necrotic resistance you would have to add that to your racial trait as well).
You don’t need to, you can simply use the subrace you want as a template and then check the box labled “is variant” which will turn that subrace into a variant race without changing anything else. Then add in your variant trait to replace the base race trait and you’re good to go.
For example, I want an Aasimar with fire resistance instead of radiant resistance. Is there a way for a subrace to get rid of the resistance of the base aasimar?
No, but there is a way for a Variant Race to do it. Make a “Granted” trait for the Variant race and under the dropdown labeled “REPLACE BASE RACE RACIAL TRAIT” choose “Celestial Resistance.” That will cause whatever you make for your homebrew variant racial trait to replace the whole base trait (so if you intend to keep the Necrotic resistance you would have to add that to your racial trait as well).
Creating Epic Boons on DDB
DDB Buyers' Guide
Hardcovers, DDB & You
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Good to know, too bad I can't make variants for subraces
You don’t need to, you can simply use the subrace you want as a template and then check the box labled “is variant” which will turn that subrace into a variant race without changing anything else. Then add in your variant trait to replace the base race trait and you’re good to go.
Creating Epic Boons on DDB
DDB Buyers' Guide
Hardcovers, DDB & You
Content Troubleshooting
Huh that worked! Thanks!