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What it says on the tin: a wilder subclass for the AU Mystic. To my knowledge this is the most recent version of that class. I'm also assuming you need 13 Int to multiclass in and out of Mystic (and I don't think that should change for this subclass).

Alternate Psionic Source
Wilders obtain their psionics powers from an inborn affinity for psionics, instead of the usual strict discipline of most mystics. As a result they use charisma instead of intelligence

Alternate Psionic Ability
Charisma is your psionic ability for your psionic disciplines. You use your Charisma modifier when setting the saving throw DC for a psionic discipline or when making an attack roll with one.

Discipline Save DC = 8 + your proficiency bonus + your charisma modifier

Discipline Attack Modifier = your proficiency bonus + your charisma modifier
I'm not sure this works in 5e? At the very least, you choose the mystic subclass at 1st level, so you don't need int beforehand.

Elude Touch
While you are not wearing any armor, your armor class equals 10 + your Dexterity modifier + your Charisma modifier. You can use a shield and still gain this benefit.

Wild Surge
Starting at 3rd level, when you spend psi points to manifest a psionic power, you can choose to perform a wild surge, allowing your passion and emotion rise to the surface.

When you use this ability, roll a wild surge die, which is a d6. On a roll of 5 or higher, you can manifest your power as if you had spend an additional psi point on it, to a maximum of your psi limit. If you roll a 1, you must spend an additional psi point in order to manifest the power. You must have psi points remaining equal to the new cost of the power or the ability fails.

At 6th level, your wild surge die increases in size to a d8. At 14th level, it increases in size to a d10.
This is intended to be a 5e scaled version of wild surge, with a remotely sensible version of Psychic Enervation. Doesn't affect that many abilities (specifically the scaling ones), but it should conserve a number of points between long rests.

Surging Euphoria
Starting at 6th level, when you use your wild surge, you gain advantage on your next attack roll or saving throw before the end of your next turn.

Volatile Mind
From 14th level, creatures must spend an additional psi point on any power which targets you. This does not count against the psi limit for that power.

Enhanced Wild Surge
At 14th level, the power of your wild surge increases. When you use your wild surge die and manifest your power as if you had spent an additional psi point on it, the additional psi point does not count against your psi limit.

The rest of the wilder toolkit. I hope they're fairly weak, given the wild surge also gets slightly better reward and slightly lower risk at the same levels.