The objective of this presentation is to provide a buffed yet balanced and more setting-encompassing alternative to the already introduced Changeling race.
Ability Score Increase. When determining your character’s ability scores, increase one score by 2 and increase a different score by 1, or increase three different scores by 1. You can't raise any of your scores above 20.
Creature Type. You are a Humanoid.
Size. You are Medium or Small. You choose the size when you select this race.
Speed. Your walking speed is 30 feet.
Changeling's Instincts. Your mind and senses have adapted to pick up on even the subtlest of social nuances. You have proficiency in the Insight skill. You also add a +3 bonus to your passive Wisdom (Insight), Wisdom (Perception), and Intelligence (Investigation) scores to discern and navigate through social cues, as in cultural expectations, impersonations, languages, etc.
Shapechanger's Adaptation. When you select this race, choose one of the options below.
Alter Ego. As an action, you can change your appearance and your voice. You determine the specifics of the changes, including your coloration, hair length, and sex. You can also adjust your height and weight and can change your size between Medium and Small. You can make yourself appear as a member of another race, though none of your game statistics change. You can’t duplicate the appearance of an individual you’ve never seen, and you must adopt a form that has the same basic arrangement of limbs that you have. Your clothing and equipment aren’t changed by this trait.
Personal Calling. As an action, you can alternate between your changeling form and your preferred form, as in the Alter Ego trait. You have advantage on Charisma (Deception) checks to calm suspicions when the identity of your preferred form is questioned, and you are proficient with one tool of your choice. Moreover, when you make an ability check using any skill or tool given as a proficiency by your racial traits, you can give yourself advantage on the check before rolling the d20. You can give yourself advantage in this way a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.
Changeling's Fluidity. As a reaction, you can turn a critical hit on you into a normal hit. Once you use this trait, you can't use it again until you finish a short or long rest. You also have advantage on ability checks you make to escape a grapple and can move through the space of any creature that is of a size larger than yours.
Linguistic Adaptability. You can read, speak, and write one additional language of your choice. It takes you half as long to learn a new language than most races (Standard rules is 250 days, it takes you 125 days).
Skill Versatility. You gain proficiency in one skill of your choice.
Fey Ancestry/Slippery Mind. You have advantage on saving throws against being charmed, and magic can't put you to sleep.
Languages. Your character can speak, read, and write Common and one other language that you and your DM agree is appropriate for the character. The Player’s Handbook offers a list of languages to choose from. The DM is free to modify that list for a campaign.
So does this presentation accomplish its objectives?
Best Answer
This is not balanced and has a few minor issues
First, if you take the book races to be the standard of balance, then almost by definition, if you buff an existing book race to be more powerful, it will be unbalanced against that race. This is essentially taking the Changeling form Mordenkainen Presents, and adding additional powers and options.
Now, not all book races are of exactly the same power, and maybe you think the Changeling from Mordenkainen Presents is on the weaker side. Detect Greater Balance, seems to think so, valuing it at 24 points, while the recommended target is 28, and a range for homebrew from 25 to 31 (this is a tool based on Detect Balance, and expanded for the newer races). To evaluate your changes, I will score the value of the deviations from that standard Changeling:
Changeling Instincts grants only one skill instead of two, but in exchange +3 to three skills. One skill proficiency less is worth -2 points. The +3 however is during tier one and two play on average comparable to a proficiency (because your proficiency bonus will range from +2 to +4), and tier one and two is where most play happens. So for practical purposes, unless you play a very high level campaign, this is the same as having proficiency if you do not have the skill, or expertise if you have it. That is even better than proficiency. Expertise on a Subset on a Skill is worth 2 points, full expertise 4 points. This will essentially apply always for Insight (as insight is a social skill), and on a subset for Perception and Investigation, so it is worth 8 points. Net effect: -2 +8 = +6 points.
Skill versatility: one more skill proficiency of choice, worth +3 points.
Fey Ancestry. Worth +2 points.
Languages and Linguistic Ability: Separating these is a bit confusing, I will treat this as if you can speak common and two languages of choice. Common and 2 or 3 languages is worth 1 point. I think the faster learning ability is a ribbon at best, most campaigns do not have idle time for hundreds of days, but even if they do, Detect Balance does not value 3 added languages higher than two. +1 point.
Shapechanger's Adaption, your first option is equal to the book Changeling's, but you provide two more options. Even if they are not more powerful in and of themselves, choices are more powerful, as you can pick the one that harmonizes best with your overall build. Detect Greater Balance values Shapechanger at 6 points, and the other options seem to be in the same range. I'd give at least 2 more points for the flexibility to pick. +2 points.
That in total gets you +6 +3 +2 +1 +2 = +14 points, on top of the 24 baseline chassis. That is 38 points; even if you count the alternate options on shapechanging for no value, it still is 36 points, clearly above the recommended range of power for homebrew.
Lastly, I don't really see how this is "more setting-encompassing" than the published Changeling. You can play the book changeling in any setting just fine, and Eberron has their own changeling variant for the setting already. You only complicate the race by trying to combine features from all different versions into one with lots of options.