I am planning on making a race that basically has the Breath Weapon trait  but without the the different damage types to choose from. Anyone know how to do that ? (recreate Breath Weapon without the different draconic ancestry options )

That’s easy. Which damage type do you want, how many times per day do you want, and do you want the damage to scale?

Sorry for the late reply! I want it to deal psychic damage, I want it to be usable once per long rest and I want the damage to scale basically the same as the dragonborn . Thanks !

Okay. For this I am assuming a cone, and since it is Psychic damage I am assuming Int instead of Con as the ability, and switched the Saving throw from Dex to Int. If you want it to be a Line or to use Con as the ability, or to change the Saving throw you will just have to alter it to match your preference. I also personally suggest you change it to once per Short Rest, but you asked for Long Rest so that's what I'm giving you.

For your race, make a feature called whatever you want it to be named. For the sake of these instructions I am calling it “Psychic Blast.”

For the snippet put this:

As an action once per long rest, emit a psychic blast in a 15 ft. cone (INT DC {{savedc:int}}, half damage on success) for 2d6 Psychic Damage [6th] 3d6, [11th] 4d6, [16th] 5d6

For the Description put this:

You can use your action to emit a blast of psychic energy. When you use your psychic blast, each creature in the area of the blast must make an Intelligence saving throw. The DC for this saving throw equals 8 + your Intelligence modifier + your proficiency bonus. A creature takes 2d6 psychic damage on a failed save, and half as much damage on a successful one. The damage increases to 3d6 at 6th level, 4d6 at 11th level, and 5d6 at 16th level. After you use your psychic blast, you can't use it again until you complete a long rest.

SAVE!!

Then you will have to scroll down to “Actions” and “Add Action.”

• Action Type—>General
• Name—>Emit Psychic Blast
• Ability Score Type—>Int
• Save Type—>Int
• Dice Count—>2
• Die Type—>d6
• Effect one Save Success—> “Half Damage”
• Damage Type—>Psychic
• Display as Attack—>Yes
• Range—>15
• Area if Effect Type—>Cone
• Area if Effect Size—>15
• Activation Type—>Action
• Reset Type—>Long Rest
• Snippet—>Same as the other Snippet

SAVE!!!

You will then have to go back and “Edit” the action you just created. Scroll all the way to the bottom until you see “Limited Use” and “Level Overrides.”

Add Limited Use Data

• Number if Uses—>1

SAVE!!!

Add Level Override (You will have to add a total of three overrides for this to work.)

First one:

• Level—>6
• Dice Count—>3

SAVE!!!

Second one:

• Level—>11
• Dice Count—>4

SAVE!!!

Third one:

• Level—>16
• Dice Count—>5

SAVE!!!

Then re-save the Action, then re-save the Feature, then re-save the whole race. That will trigger the system to pick up the changes, after that just be patient for the system to push those changes through to the character sheet.

I hope this has been helpful.

Thank you ! 

Here is the finished product: https://www.dndbeyond.com/races/406846-half-fomorian (ignore the part that's still the same as the Goliath )

I followed the instructions on this but for some strange reason the ability is not picking up as a saving throw, but is assigning it as an attack with a to-hit value. Any idea why that is?

Looking forward to if you could help

Quote from Homebrewry >>

I followed the instructions on this but for some strange reason the ability is not picking up as a saving throw, but is assigning it as an attack with a to-hit value. Any idea why that is?

Looking forward to if you could help

 
You probably designated an “Attack Range,” remove that.