In System Shock 2, Psionic disciplines, or PSI powers, are abilities that the player uses to cause a variety of effects in the game. Some disciplines are offensive, some defensive, some affect the player's statistic or skill values, some result in status effects, and others provide some other special ability. Psionic disciplines require the player to wield a PSI amp to use, and consume PSI points when activated.

Since psionics fills the same role that magic does in a fantasy RPG, Psionic disciplines correspond to individual spells. Carrying this analogy through shows that the PSI amp fills the role of a wand, PSI points like magic points or spell points, and PSI tiers like spell levels.

New psionic disciplines are unlocked at PSI upgrade units using cybernetic modules.


Psionic disciplines are grouped into five tiers, or levels. The number of the tier corresponds to the number of PSI points required to activate any particular discipline from that tier. That is, Tier Four disciplines require four PSI points to use. Each tier contains seven disciplines, giving a total of 35 available disciplines in the game.

Prior to acquiring any new psionic discipline, the player must have also unlocked the tier to which that psionic discipline belongs. This is also done at PSI upgrade units, and costs the same number of cybernetic modules as a discipline for that tier. Tier unlock upgrades are not disciplines, and have two passive effects: They make it possible to unlock psionic disciplines at that tier, and they provide a permanent increase in PSI points equal to twice the level number. Thus, unlocking Tier Five increases maximum PSI points by ten (2 × 5). Tiers need not be unlocked in order, or at all.

After training, all O.S.A. Agents start with Tier One and Tier Two unlocked, along with the Projected Cryokinesis discipline and any two of the other six Tier One disciplines.


PSI disciplines can be overloaded to increase their effectiveness, by holding down the left mouse button. A progress bar will appear in the center of the screen, filling as you continue to hold the mouse button. Once it reaches the yellow box at the right side of the bar, release the button and the PSI power will be cast with a bonus of +2 to your PSI stat, to a maximum effective PSI of 8.


The overload bar

Missing the yellow box by releasing too early uses the PSI power at its normal level. Releasing too late causes PSI burnout. The power will fail, and you take damage unless you've installed the Power Psi upgrade. The progress bar moves faster for higher tier PSI disciplines, increasing the difficulty of overloading.

Cybernetic module costs

The cost of any PSI upgrade unit item depends on the tier and difficulty level. The cost of any given tier is the floor of one-and-two-thirds times the cost of the next tier down. That is, a Tier Two upgrade costs one-and-two-thirds times what a Tier One upgrade costs, rounded down. Tier Three the same with respect to Tier Two, and so on. These values are then scaled according to the difficulty level.

Difficulty level versus tier impact on PSI upgrade costs (in cybernetic modules)
T1 T2 T3 T4 T5

Easy (×0.85)

2 4 6 10 17

Normal (×1.00)

3 5 8 12 20

Hard (×1.39)

4 6 11 16 27

Imposs. (×1.79)

5 8 14 21 35

While there are technically enough cybernetic modules in the game to obtain all 35 psionic disciplines, the cost on Hard and Impossible would be over half of them. As a result, few players opt to get every psionic discipline.

Psionic disciplines by type

Offensive disciplines

These are disciplines that cause damage to others.

Tier Base dmg. Dmg. type Notes
Projected Cryokinesis 1 3 + 1×PSI Cold
Localized Pyrokinesis 2 5 per 2 sec. Incendiary Follows player when active; AOE: 5 + 1×PSI ft.; duration: 15 + 8×PSI sec.; does not cancel Photonic Redirection if activated first; renders player immune to incendiary damage
Projected Pyrokinesis 3 5 + 2×PSI Incendiary
Cerebro-Energetic Extension 4 18 Standard Smasher gives +6
Soma Transference 5 10 + 5×PSI Special Harms organic enemies only (except swarm); transfers HP to player's HP pool
External Psionic Detonation 5 30 Psionic AOE of 10 ft.

Defensive disciplines

These reduce damage from a variety of sources.

Tier Dmg. Reduction Dmg. Types Notes
Psycho-Reflective Screen 1 15% All 20 sec. + 30 sec./PSI
Neural Decontamination 2 80% Radiation absorption 10 sec. + 5×PSI sec.

Does not reduce accumulated dose

Energy Reflection 3 50% Energy 20×PSI sec.
Neural Toxin-Blocker 3 100% Toxin absorption 10 sec. + 5×PSI sec.

Does not reduce accumulated dose

Metacreative Barrier 5 Fixed barrier All Barrier HP is 150 + 50×PSI for PSI from 5–10
Psycho-Reflective Aura 5 60% All 10 sec. + 20×PSI sec.

Healing disciplines

These disciplines directly refill the player's hit point pool.

Tier HP Notes
Cerebro-Stimulated Regeneration 2 2×PSI (instant) PSI effect cap is 10 instead of 8
Advanced Cerebro-Stimulated Regeneration 5 5×PSI (instant) PSI effect cap is 10 instead of 8
Soma Transference 5 10 + 5×PSI (instant) Must target an organic enemy (except swarm)

Status disciplines


These disciplines affect player stats that are used in a variety of calculations. In most RPGs these would be called "buffs".

Tier Statistic Degree Duration Notes
Neuro-Reflex Dampening 1 Ranged weapon recoil -100% 60 + 20×PSI sec.
Psychogenic Agility 1 Agility +2 120 + 60×PSI sec.
Psychogenic Cyber-Affinity 1 Cyber-Affinity +2 120 + 60×PSI sec.
Anti-Entropic Field 2 Weapon decondition rate -100% 10 + 20×PSI sec. Ranged weapons
Adrenaline Overproduction 2 Melee weapon damage ×(0.13×PSI2 + 1) 10×PSI sec.
Psychogenic Strength 2 Strength +2 120 + 60×PSI sec.
Recursive Psionic Amplification 2 Psionic ability +2 10 + 10×PSI sec. Psi point costs doubled when active
Photonic Redirection 4 Player invisibility 100% 5 + 5×PSI sec. Prevents all enemies and cameras from detecting the player
Psychogenic Endurance 4 Endurance +2 120 + 60×PSI sec.
Remote Circuitry Manipulation 4 Cyber-affinity and Hacking Set at 0.5×PSI (round up) One hack attempt Hack software ignored, O/S upgrades ignored, inherent HCK/CYB ignored; allows ranged hacking; PSI effect cap is 10 instead of 8

Non-self targeted

These disciplines cause status effects to others. In many RPGs these would be called "debuffs".

Tier Effect Degree Duration Notes
Remote Electron Tampering 1 Decrements XERXES alert timer 5 + 5×PSI sec. Instant
Psionic Hypnogenesis 3 Calmed status Biological only 20×PSI sec. Psi-Reavers immune, Swarm probably immune; immediately cancelled if damage taken
Photonic Redirection 4 Enemy awareness 0% 5 + 5×PSI sec. Prevents all enemies and cameras from detecting the player
Electron Suppression 4 Paralyzed status Mechanical only 3×PSI sec. Not interrupted by damage; may affect SHODAN avatars
Imposed Neural Restructuring 5 Charmed status Biological only 10×PSI sec. Will attack any non-human entity (i.e., not players); Psi-Reavers immune, Swarm probably immune; immediately cancelled by damage from a human entity

Other disciplines

These disciplines cause a variety of effects.

Tier Description Duration Notes
Kinetic Redirection 1 Pulls targeted object towards player 1×PSI sec. Movement speed is 60
Molecular Duplication 3 Chance to duplicate one "clip" of a consumable inventory item; consumes nanites Instant Chance is (30 + 10×PSI)%; nanite cost is the normal difficulty hacked replicator cost; cannot duplicate Psi Hypos; can replicate Psi Boosters and worm ammo
Electron Cascade 3 Charges portable battery or powered item Instant Adds 20×PSI percent charge, up to maximum charge allowed by Maintenance skill
Enhanced Motion Sensitivity 3 Shows nearby enemies on minimap 30×PSI sec.
Remote Pattern Detection 4 Shows nearby items on minimap 60×PSI sec.
Molecular Transmutation 4 Converts one "clip" of inventory items into nanites Instant Amount recovered depends on PSI, amount of clip consumed, and an item-specific factor; PSI effect cap is 10 instead of 8; may produce more nanites per clip than the recycler, but the PSI point cost matters
Instantaneous Quantum Relocation 5 Teleport to a designated point on the current map Instant First use designates destination, second use teleports

See also

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