For when you have an awesome idea for your character but aren’t quite sure how their parent’s races would mix (I’ll be comparing a Half-Orc/Tiefling and a Tiefling/Dwarf for my examples). A lot of this can be discussed with your DM as well, if you need any help fitting it into their campaign! And remember, when in doubt, roll a d20 to figure out the outcome.
Warning: There will be opportunities to be creative and to world-build
Find out what bonuses each race gets to their scores. Most races in the Player’s Handbook only have one ability score increase, but some (Dragonborns, Half-Orcs, and Tieflings) have two, and Humans have a +1 increase to all of their scores.
Half-Orcs receive a +2 to their strength and a +1 to their constitution, while Tieflings have a +1 Intelligence score and a +2 to their Charisma. Dwarfs only get +2 to their Constitution.
Then figure out how you’re going divide those points up. A lot of this is touch and go, and I once again encourage you to work with your DM to find what works best for you. I like to keep it within a +3 increase max (with the exception of Human, who’s stat increases are bs. Going with Half-Elf stats as my base, a Half-Human gets +2 to whatever dominate trait the other race has, and +1 to two stats of your choice (so a half-gnome would have +2 INT and +1 to two other stats)).
I gave my Half-Orc Tiefling +2 STR (from the Half-Orc) and +1 INT (from the Tiefling), keeping in mind that that this character was a strength build for the campaign.
The Tiefling Dwarf, on the other hand, had +1 CON, +1 INT, and +1 CHA
If your size is the same on both of the parent race’s tables, then congrats! You’ve already got it figured out!
Tieflings, Half-Orcs, and Dwarfs are all Medium. I didn’t have to do any work here :)
However, if you’ve got a small race and a medium race, or a medium race and a large race, you (or your DM) are gonna have to do some funky maths (which shouldn’t matter, because you’re playing D&D. This whole game is maths).
Take the average size of both races. We’re using 106 cm (about 3′6; small) and 195 cm (about 6′6, medium). Add those two numbers together (301) and divide that by 2 (the amount of numbers you just added together). Now we have 150.5 cm, which is about 4 foot 11 inches (medium).
If you already know your exact height, though, just take a look at this helpful table right here to find out your size.
< 4ft = Small or smaller
5ft to 8ft = Medium, and
> 8ft = Large or larger
Speed is a difficult thing to figure out, but once again, if the numbers match then the speed is the same. If they don’t, then factor in size. Small? Your base speed is 25ft. Medium? 30ft. Thickset (Looking at you, Dwarfs)? We’re back to 25ft.
The Half-Orc/Tiefling is medium, and both of their parent’s base walking speed is 30ft. Their base speed is also 30ft.
The Tiefling/Dwarf is medium, but her parents both had different walking speeds. Her build is on the shorter side, and closer to that of a Dwarf’s, so her base speed is 25ft.
This is one of the harder parts, in my opinion; finding a way to balance one races traits with an other’s to make a well-rounded character. The general rule-of-thumb here is “If both parental races have the same trait, then the character automatically inherits it.”
Half-Orcs, Dwarfs, and Tieflings all have Darkvision, so both my Half-Orc/Tiefling and my Tiefling/Dwarf have it.
Think about the details of this character. How they carry themselves; where they were raised and how they grew up. Consider what would be a given trait from one of their parents. Get creative with it (and talk to your DM about potential chances at world-building)!
Also bring into consideration what traits could be genetic (like what colour hair and eyes you were born with), and what traits would be learned (like what languages you grew up knowing. My friend is French Canadian, for example, so she grew learning both French and English.)
My Half-Orc/Tiefling was raised in a very formal household, so the way they carry themselves is very sharp (picture the von Karmas from Ace Attorney).
They have the Half-Orc’s Menacing trait for that aspect. They inherited Hellish Resistance from their Tiefling father, and Infernal Legacy because they grew up with him.
My Tiefling/Dwarf, on the other hand, was primarily raised in dwarfish mines, and doesn’t really remember her Tiefling mother.
She inherited Hellish Resistance, but she does not have Infernal Legacy. She also has Dwarven Resilience, Dwarven Combat Training, Tool Proficiency, and Stonecunning, because of how and where she was raised.
There’s no methodological way to determine what languages your character might speak, so I’m once again asking you to consider their backstory. If both races have a common language between them, then use it!
I have no other advice for what languages they’d speak other than “Use their backstory, or use this as a chance to form their backstory.”
I hope this helps with your character creation! Happy New Year, stay safe!