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.
Tiers
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.
Overloading
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 10 (however, for that the player needs to have PSI 8 before casting).
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 or you have high enough PSI (only 8 is wholly safe tho). The progress bar moves faster for higher tier PSI disciplines, increasing the difficulty of overloading. It is worth noting that upgrading the PSI stat also makes the yellow overload box bigger, easing 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.
| 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 the disciplines that cause damage to others.
| Tier | Base dmg. | Dmg. type | Notes | |
|---|---|---|---|---|
| Projected Cryokinesis | 1 | 3 + PSI | Cold | |
| Localized Pyrokinesis | 2 | 5 per 2 sec. | Incendiary | Follows player when active ; AOE: 5 + 1×PSI ft. ; duration: 7 + 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 adds 6 to its basic damage |
| Soma Transference | 5 | 10 (+5×PSI for each PSI >5) | Special | Harms organic enemies only (except Swarms) ; transfers HP to player's HP pool ; PSI effect cap is 10 instead of 8 |
| 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×PSI sec. |
| 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 each PSI >5) ; PSI effect cap is 10 instead of 8 |
| 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 + 5×PSI (instant) | PSI effect cap is 10 instead of 8 |
| Soma Transference | 5 | 10 (+ 5×PSI for each PSI >5) (instant) | PSI effect cap is 10 instead of 8 ; must target an organic enemy (except Swarm) |
Status disciplines
Self-targeted
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 | Cybernetic Affinity | +2 | 60 + 30×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 cameras and all enemies (but SHODAN and her avatars) from detecting the player |
| Psychogenic Endurance | 4 | Endurance | +2 | 120 + 60×PSI sec. | |
| Remote Circuitry Manipulation | 4 | Cybernetic Affinity and Hacking | Set at 0.5×PSI (round up) | One hack attempt | Inherent Hack/CYB, Hack software & O/S upgrades are ignored ; allows ranged hacking ; PSI effect cap is 10 instead of 8 (although 9 is enough) |
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 | PSI effect cap is 10 instead of 8 |
| Psionic Hypnogenesis | 3 | Calmed status | Hybrids, Cyborgs, Arachnids | 20×PSI sec. | Immediately cancelled if damage taken |
| Photonic Redirection | 4 | Enemy awareness | 0% | 5 + 5×PSI sec. | Prevents cameras and all enemies from detecting the player ; doesn't affect SHODAN and SHODAN avatars |
| Electron Suppression | 4 | Paralyzed status | Only pure Mechanical | 3×PSI sec. | Not interrupted by damage ; doesn't affect SHODAN and SHODAN avatars |
| Imposed Neural Restructuring | 5 | Charmed status | Hybrids, Cyborgs | 10×PSI sec. | Will attack any non-human entity (i.e., not players) ; 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 | 2×PSI sec. | PSI effect cap is 10 instead of 8 ; 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 specific items on minimap | 60×PSI sec. | Doesn't show all types of items. |
| 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 | Teleports to a designated point on the current map | Instant | First use designates destination, second use teleports, clearing the marker |