Psi powers are an additional way that you can augment some human soldiers in X-Com: Enemy Unknown. You can only acquire psi powers on your soldiers if you have built psionic labs. These labs allow you to test your soldiers. Some will have the gift granting them psi powers. Psi powers improve through use rather than from gaining levels. After enough use of the level 1 power you will unlock the level 2 powers and after more use the level 3 powers. There is only one level 1 power, but two each of the next levels, and you must select one when your soldier reaches that point. The following guide will give you all the information you need about using psi powers.
Mindfray (Level 1) – This will deal 5 damage to a non-robotic target and reduces aim and will of that target by 25 for two rounds. Unlike weapons, psi powers completely ignore defense, cover, and aim penalties. Accuracy is entirely based on the will of the target and the psionic character. About half the enemies in the game have a will of 0, which makes this basically sure thing damage against those enemies. Use this when an enemy is hiding behind cover or when you want to set up a more powerful psi power from another character. Also, if you know you can’t kill an enemy in a single round, this is a great way to reduce that enemy’s aim for a round.
Psi Inspiration (Level 2) – Psi Inspiration reduces panic from nearby allies and increases their will by 30. You can use this reactively after an ally has been hit with a psionic attack, but it is better to use it just before your troops engage psionic enemies. Prevention is generally better than response in X-Com: Enemy Unknown. If you have the Enemy Within expansion this will stack with gene mods that also increase psi. Select this power if your squad has a lot of soldiers with low will.
Psi Panic (Level 2) – Psi Panic can cause a non-robotic enemy to panic for two rounds. This is great if your squad is outgunned by a bunch of low will enemies. This won’t happen often, but as a safety net, it isn’t a bad power. Unfortunately, this power is a lot more difficult to use than Psi Inspiration for increasing the level of your soldier’s psi powers. One soldier with this power is good, but more will probably go to waste.
Telekinetic Field (Level 3) – Telekinetic Field is outstanding and probably one of the main reasons to invest in psionic abilities. The psionic character can create a large field that gives a boost of 40 to the defense of all allies. In conjunction with cover or suppression fire, this basically makes your troops incapable of being hit. This is a critical power for large open maps and you’d like to have at least two soldiers with this ability if possible.
Mind Control (Level 3) – This is pretty much either the best psi power in the game or entirely worthless, depending on the whims of the random number generator. If successful, Mind Control will convert a non-robotic enemy to your team for 3 rounds. If not, you wasted an action. While you will generally be tempted to use this on the biggest, baddest enemy around, you should instead target grunts with it. They are more likely to have a low will and they should still deal relatively high damage. Since you aren’t allowed to attack an enemy under mind control, affecting a grunt means you have one more ally attacking a powerful enemy, probably from point blank range.
Rift (Special) – Just before the final mission of the game, one soldier on your squad gains the Rift psi power. It is essentially a psionic rocket that deals massive damage to all enemies and even affects robotic enemies. You get to choose what soldier gets this, so it is probably best to put it on a support soldier, who is likely to have a spare action to use this attack.