An Avatar with Crown of Disgust kind of gives off a far realms vibe.
Order of Avatar Mystics are going to want to poach Pyschic Restoration from the Immortal by level 6 or they will almost never get any advantage from Avatar of Healing. They have no native healing discipline, so it's a nearly useless feature without it.
Soul Knife + Psychic Consumption + Psychic Restoration + Mystic Restoration = Psychic Vampire Action. Kill something with your soul knife, gain 2 psi points, spend them on Psychic Restoration to heal yourself, then use a bonus action to use Mystic Restoration for bonus healing.
Giant Discipline + auras extend the area you auras reach, so oddly it's good for Avatars. It can also give major range to a soul knife's soul knives and extra damage.
Soul Knives will mostly want to poach from Nomad and Immortal lists.
Nomads are all about knowledge and movement, so you have a ton of different ways to focus your Nomad depending on power choices.
Immortal is good at being tough, but without martial weapons isn't actually good in melee combat. They are extremely good at altering their bodies.
Rogue's will find Soul Knife extremely tempting, especially if they don't have darkvision (Mastery of Light and Darkness as their 1 discipline).
The build that appeared to my mind is Order of the Avatar.
First Disciplines and talent Pyschic Restoration, Mantle of Awe, Mantle of Command, Energy Beam.
By level 3 add Mastery of Light and Darkness so I can summon shadows, see in Magical Darkness, create light including giving my allies advantage against a target.
For future Disciplines, Crown of Disgust, Mantle of Joy, Giant Growth, Telepathic Contact, Beastial Form, Mastery of Water, Talents Delusion, Pyshic Hammer, and Mystic Charm.