Mirrorkin

Sorcerous Origin
Notes from the Nails: this subclass came out on top in a recent homebrew contest on GitP. Ah, victory is sweet!

Mirrorkin

One of your ancestors came from beyond the looking glass; a strange world where everything is a twisted reflection of the true reality. As such, you have inherited amazing powers of mimicry and illusion that allow you to copy other people’s abilities. To fight against you is almost akin to fighting one’s own mirror image, something few warriors would relish.

Mimic Trait
When you choose this origin at 1st level, you gain an uncanny ability to mimic other people. As an action, you can choose a humanoid you can see within 60 feet and gain one item of your choice that they possess from the following list (even if they only possess it temporarily):

• One special sense, such as darkvision or tremorsense.
• One movement speed, such as a swim or climb speed.
• One skill, tool or instrument proficiency.
• One damage resistance.
• Their accent, verbal ticks and mannerisms.

     You can keep this trait as long as you are within 60 feet of the target, or until you use this ability again.

Reflect Magic
At 6th level, you can turn your skin into a shimmering mirror that reflects magic. Whenever you succeed on a saving throw against a spell or cantrip, you can use a reaction and spend a number of sorcery points equal to the spell’s level (1 sorcery point for cantrips) to reflect the spell’s energy back against its caster. When you do this, the caster must make the relevant saving throw against their own spell save DC, exactly as if they had been the original target or within the area of the spell.

Copycat
By 14th level, you have developed your mimicry to the point where you can mirror the unique and powerful abilities of those around you. As an action on your turn, you can perform any action that has been performed by a humanoid (other than yourself) you can see within 60 feet within the last minute. Any prerequisites that would normally be required for the action (such as brandishing of holy symbols, spending of ki points or consumption of items) are waived when you use this feature, unless it is a spell or required the use of a spell slot, in which case you must still expend the relevant spell slot. If the ability forces targets to make a saving throw, you can use your Sorcerer spell save DC.
     Once you have used this ability, you must complete a long rest before you can use it again.

Perfect Duplicate
At 18th level, you can duplicate yourself and others with ease. You learn the spells disguise self and mirror image if you do not know them already, and you can cast them at-will without expending a spell slot.

Changelog: 10/18/2020: Copycat requires spell slots whenever the ability being copied does.