Copycat

You are able to copy opponents' attacks, blocks and spells to get an even match.  The stronger you get the stronger the attacks you can mimic are.

Mimicry

As a reaction, make a dexterity check against a DC of 16 minus your rogue level.  On a success, you are able to mimic the non-attack action of an ally.  You can do this up to a number of times per short rest equal to your rogue level (up to a maximum of 6 times per short rest).

Mystic Mimicry

You learn all spells on the mystic mimic spell list.  You have the same spell slot table as an arcane trickster.  Your spellcasting ability is dexterity.

Imposter

You gain the ability to unerringly mimic another person's speech, writing, and behavior. Your ruse is indiscernible to the casual observer. If a wary creature suspects something is amiss, you have advantage on any Charisma (Deception) check you make to avoid detection.