Is a humanoid mimic race overpowered?

Question

I am currently working on a Homebrew D&D 5e race and one of the ability's I am working on is the power to mimic any object that you are familiar with unless is's a gadget like a magic orb or such (Books get a pass). I have tried testing it, but couldn't since everybody I knew that played D&D was offline and working so here I am asking for help.

First of all, the race is of abyssal origins without sporting the colors that remind people of hell, actually they look more like they are from the void so they can hide in the shadows. Their gigantic glowing white eyes help them see in the dark making the them good guides and their speed can help them race circles around enemy's though they aren't good with charisma since they lived in the shadows for so long. They aren't very trusted for partly the same reason as tieflings, Their alignment usually leans towards neutral but ones that want more freedom lean towards neutral chaotic and ones that trust other races more are lawful good or neutral good as. They are as big as Shy Guy from SCP with the body of a healthy human being but still with skinny arms that are just thick enough to not show bones. Basically it's what the title says except with better eyesight and a Shy Guy like humanoid form replacing the original mimic form. I am going to far in. It's like this mimic homebrew race from dandwiki but with more powerful options.

Racial traits weren't listed so here we go:

Ability Score Increase. Dexterity +2, Constitution +3

Long limbed. Your long arms allow melee to reach up to 5 extra feet

Light footed. You are fast and nimble. Your speed gains 10 extra feet

Shape changer. You can change your shape into something you are familiar with, when you change shape you change your height.

Darkvision. You can see 60 feet in the dark but only see black and white.

Medium. Your default size is medium.

Answer 1

It's overpowered

Medium size and darkvision are normal features.

Ability score increases of +2 and +3 are higher than normal. Most races have +2 to one ability score and +1 to another. Mountain dwarf has +2 Str / +2 Con.

An extra 5 feet reach is somewhat powerful. You can use this plus a reach weapon to hit targets 15 feet away. Even a normal weapon, reach is equivalent to increasing a die type; you're able to wield e.g. a 2d6 greatsword at reach rather than a 1d10 reach glaive.

It's not clear what's meant by "Your speed gains 10 extra feet" isn't normal phrasing. A race has a speed, not a speed bonus. If this means 10 feet faster than the D&D wiki entry, that's 35 feet. Combined with the increased reach, it has an enormous amount of battlefield mobility.

The shapechanging ability is overpowered. The changeling from Eberron can change appearance at will, but has to retain it size and humanoid form. This mimic can change into anything and can change height. It can become any equipment, isn't necessarily forbidden from changing size class (as written). Its number of possible forms is unbounded, which makes it highly versatile, and therefore more useful than might be first seen (e.g. turn into gold as a scam, turn into a hot air balloon to fly, etc). If it works like the D&D mimic, its form is indistinguishable from an object, which would be a very overpowered ability to hide.

Answer 2

Needs adjustments

I think that as it stands the hombrew seems quite unbalanced (overpowered) for a few reasons:

• ASI of Dex +2 and Con +3: Very unbalanced. the ASI spread for most races is normally +2 and +1. Some only have a +2 such as the Kenku or Kobolds. If you add +3 to any ability score I would impose a penalty or -2 to -4 depending on the overall balance of the race.
• long-limbed: It could be balanced if the rest of the racial traits are. The Bugbear has this trait for instace. At first glance a 10 ft. range does not seem like much but it can be a significant advantage in avoiding opportunity attacks due to the fact that the majority of creatures will only have a 5 ft melee range. The opportunity attack gets triggered when "a hostile creature you can see moves out of your reach" (PHB, p.195). This in practice means that you can carry out melee attacks against creature with a 5 ft. reach "at arms length. This works similar to a flying creatures trait of "flyby". So the humanoid mimic can do a "hit and run". This, in conbination with the "light footed" trait makes it unbalanced.
• light-footed: It could be balanced. Some races such as Wood Elves, Centaurs or Satyrs already have a base walking speed higher than 30 ft. So you can just build this into the "speed" section of your homebrew race. I think this works, but I would wonder whether this fits with the flavour of a huamnoid mimic race? Does it really need to move quicker than 30 ft per round. There is always the Mobile feat if an individual player wishes to add +10 ft to their base movement (if GM allows feats).
• Darkvision. It is pretty common for quite a few of humanoid races.
• Medium. Fine, most playable races are medium-sized.

Now, to the Shape Changer feature. I think this is the essence of your homebrew race. I mean, what is the point of a humanoid mimic race that cannot shape-change right?! However, I would set a boundary about the number of times this is allowed in between short or long rests.

If I allowed a humanoid mimic race in my campaign, I would make a couple of amends and go back to the actual Mimic (MM p.220) to add a touch of flavour.

• ASI: +2 Con, +1 Dex
• Darkvision: 60 ft
• Damage resistance: Acid (in the flavour with the Mimic, but not overpowered)
• Shape-changer (limited): Either 1/short rest, or 2/long rest for 1 minute. Also I would limit the size, as in you can only turn into a medium-sized object (give examples, e.g. chair, table, chest of drawers, door, box, etc). You could add that when shape-changed it cannot be knocked prone (as per the Mimic in MM) and has advantage checks to grapple. This again is in flavour with the actual mimics.
• Then either have a base speed of 35 ft. or the long-limbed feature - but not both together. If I had to, I would opt for the long-limbed in this case, but I might even be tempted not to have either of them to be honest.

I think your homebrew has the potential of making a campaign a lot of fun - especially if you have a Druid in the mix too. Perhaps leaving a "cage" with a "bird" in it on someone's doorstep. Drum roll: what could go wrong?!

As a tip, I think it can also be helpful sometimes to look at the unofficial Detect Balance spreadsheet for 5e homebrew races to find points of comparison.