Psi short for Psionics is the Magic of the Neocron Universe the skills are mainly used by Psi Monks however Private Eyes and Spys have been known to dabble in it. Psi is broken into two major types Agressive Psi Use (PSU) and Passive psi Use(PPU). APU is your bread and butter damage spells, fire, poison, energy, psi, Ice etc.. and PPU is Heals, Shields, Boosts, Stuns and pets.
Fire medium upfront damage and a small damage over time, medium reset, short range,
Poison Minimal upfront damage but a long damage over time diration long reset, medium range.
Energy low damage upfront, no damage over time, quick reset, short range.
Lightning medium damage upfront, no damage over time, medium reset, long range
Psi High damage upfront, no damage over time, long reset, medium range
Ice Low damage but a chance of slowing oponent,long reset, short range.(the most passive of APU)
Heals Healing damage
Shelds Protecting target from a specific damage type
Boosts Spells that boost other skills and stats
Stuns they do little or no damage but slow or destract oponent
Pets This is how the PPU does its damage by manipulating soul clusters, this is a difficult manuver as most soul clusters seem to get destracted easily and will wander away if you ar not focused on telling them what to do.