Thanks for your input, Chryssis. I am very tempted to go Mystic because of some of those Disciplines, like Nomadic Step, Nomadic Mind and Beast Form.
I should mention that my DM nerfed some of the Disciplines. I didn't like most of his changes but that's how it is. Have a look (We're playing Dark Sun, to put it in context):
*Order of the Soul Knife – Soul Knife: If you roll 1 on your attack roll, you must make a Intelligence saving throw DC 10 or your knife disappears and you lose the ability to manifest them. You can repeat an Intelligence saving throw DC 10 at the end of your turns to recover this ability.
*Order of the Soul Knife – Hone the Blade: This bonus lasts for 1 minute.
Psi Points | Attack and Damage Bonus
2 | +1
5 | +2
7 | +3
*Discipline Adaptive Body – Environmental Adaptation: As an action, you or a creature you touch, becomes more resistant to the effects of extreme heat or cold (but not cold or fire damage) for the next hour, adding +1 to constitution saving throws.
*Discipline Adaptive Body –Energy Immunity (change name to Energy Reduction): As an action, you can touch one creature and give it damage reduction, of 15, to acid, cold, fire, lightning, or thunder damage (your choice), which lasts until your concentration ends.
*Discipline Bestial form –Bestial Claws: On a hit, this attack deals 1d8 slashing damage per psi point spent. Discipline Bestial form – Bestial Transformation: Flight (7 psi). Wings sprout from your back. You gain a flying speed equal to your walking speed.
*Discipline Celerity –Psychic Focus: While focused on this discipline, your walking speed increases by 5 feet and you gain +2 in Ac against opportunity attacks. *Discipline Celerity – Agile Defense: (3 psi).
*Discipline Celerity – Rapid Step: As a bonus action, you increase your walking speed by 5 feet per psi point spent until the end of the current turn. *Discipline Celerity –Surge of Action: (7 psi).
*Discipline Corrosive Metabolism –Corrosive Touch: Taking 1d8 acid damage per psi point spent.
*Discipline Diminution –Miniature Form: As a bonus action, you become Tiny until your concentration ends. While this size, you gain a +2 bonus to Dexterity (Stealth) checks and can move through gaps up to 6 inches across without squeezing. You speed reduce in 5ft.
*Discipline Diminution –Microscopic Form: As a bonus action, you become smaller than Tiny until your concentration ends. While this size, you gain a +5 bonus to Dexterity (Stealth) checks and a +3 bonus to AC, you can move through gaps up to 1 inch across without squeezing, and you can’t make weapon attacks. You speed reduce in 5ft.
*Discipline Giant Growth –Ogre form Form: (2-5 psi; conc.,1min.). Other effects remain, but now have extra damage options. Psi Points Extra damage 2 1 3 1d4 5 1d6
*Discipline Intellect Fortress–Psychic Parry: (2–6 psi). As a reaction when you make an Intelligence, a Wisdom, or a Charisma saving throw, you gain a +1 bonus to that saving throw for each 2 psi points you spend on this ability.
*Discipline Iron Durability–Iron Hide: (1–5 psi).
*Discipline Mastery of Air – Wind Step: (1–7 psi). As part of your move on your turn, you can fly up to 10 feet for each psi point spent. If you end this flight in the air, you fall unless something else holds you aloft.
*Discipline Mastery of Fire – Psychic Focus: While focused on this discipline, you gain resistance to fire damage.
*Discipline Mastery of Fire – Combustion: Takes 1d8 fire damage per psi point spent.
*Discipline Mastery of Force – Wind Step: Your base AC is 13 + your Dexterity modifier.
*Discipline Mastery of Water – Desiccate: Takes 1d8 necrotic damage per psi point spent.
*Discipline Mastery of Wood and Earth – Animate Weapon: Plus an extra 1d8 force damage per psi point spent on this ability.
*Discipline Nomadic Arrow – Psychic Focus: Attacking at long range doesn't impose disadvantage on your ranged weapon attack rolls.
*Discipline Nomadic Arrow – Speed Dart: Deals an extra 1d8 psychic damage per psi point spent.
*Discipline Nomadic Step – Psychic Focus: your walking speed increases by 5 feet.
*Discipline Psionic Weapon – Lethal Strike: Deals an extra 1d8 psychic damage per psi point spent.
*Discipline Psionic Weapon – Augmented Weapon: (3-5-7 psi; conc., 10 min.) Until your concentration ends, that weapon becomes a magic weapon with a +1 (3 psi points), +2 (5 psi points) or +3 (7 psi points) bonus to its attack and damage rolls.
*Discipline Psychic Assault– Psychic Focus: +1 bonus to damage rolls.
*Discipline Psychic Distruption– Distracting Haze: On a failed save, it takes 1d8 psychic damage per psi point spent.
*Discipline Psychic Inquisition– Hammer of Inquisition: On a failed save, it takes 1d8 psychic damage per psi point spent and suffers disadvantage on its next Wisdom saving throw before the end of your next turn. On a successful save, it takes half as much damage.
*Discipline Psychic Phantoms– Distracting Figment: On a failed save, it takes 1d8 psychic damage per psi point spent.
