I love the concept of the dragonborn genenerallygenerally, but it seems to be that the common consensus around the dragonborn as they stand in the 5th edition of D&D is that they're a bit lacklustre compared to the other official races. In playing dragonborn characters, I've generally found that the breath weapon doesn't really stay relevant once you get into the mid-levels, leaving their damage resistance as their one main gimmick.
- Ability Score Increase: You gain +2 Constitution and +1 Strength
- Size: Height/weight unchanged from PHB. Your size is Medium.
- Age: Lifespan unchanged from PHB.
- Speed: 30 feet
- Languages: You can read, speak and write Draconic and Common
- Fire Resistance: You have resistance to fire damage. In addition, while you have fire resistance from another source (such as a spell, magic item or class feature) this trait grants you immunity to fire damage instead.
- Tough Build: Your maximum Constitution score is 22 instead of 20. However, for each point that you raise your Constitution above 20 using this trait you also reduce your maximum Dexterity by 1.
- Cold Aversion: You are adapted living in places of extreme heat. Unless you have resistance to Cold damage, your aversion to the cold manifests in two ways:
- You have Disadvantage on Constitution saves made against Extreme Cold (DMG P.110)
- When you take a Long Rest you require an ambient temperature of at least 25°C (75°F77°F) for at least 6 hours, otherwise you suffer 1 level of exhaustion after finishing the rest. (Resting near a fire or keeping a lit brazier in your room or tent will provide adequate heat in most climates.) Exhaustion sustained this way can be recovered from normally, but not during the same rest that it was incurred.
- Breath Weapon: You may use your action to exhale a fiery blast in a cone whose size is equal to your Constitution score. If playing on a grid, round up or down to the nearest 5'. Each creature targeted by this attack must make a Dexterity saving roll of 8 + your proficiency bonus + your Constitution modifier, taking 2D6 fire damage on a failed save or half as much on a successful one. This damage increases by 1D6 at 5th level (3d6), 11th level (4d6), and 17th level (5d6). You may use this feature a number of times equal to your Constitution modifier (minimum of 1), and you regain all spent uses after a short or long rest.
- Fiery Assault: If you have the Extra Attack feature, you may choose to replace one of your attacks with your breath weapon. (Clarification: Other features that grant additional attacks do not benefit from Fiery Assault)
- Fiery Nature: Even though your breath weapon is not a spell, when you use your action to use your breath weapon you may treat it as though it were a 2nd level Evocation spell with a range of Self for the purposes of any features you have that can modify or enhance spell effects. For example, your breath weapon can be enhanced by a sorcerer's Metamagic, a School of Evocation wizard's Sculpt Spell ability, and benefit from the Elemental Adept feat. In addition, as a bonus action you may spend a spell slot of 2nd level or higher to recharge your inner flame, regaining a number of uses of your breath weapon equal to the level of the spell slot divided by 2, rounded down.