Used By: Medic
Energy Cost: N/A
Description: The Medic starts with this ability and may use it to heal damage done to any ground biological units, including the Protoss Zealot, Dark Templar, High Templar and all Zerg ground units. It heals 2 HP per energy.
Rating: B+
Commentary: Heal is excellent with Marines and other infantry. Works very well with stimpacked Marines. However, Medics will often run off and heal each other without proper micromanagement.

Used By: Medic
Energy Cost: 50
Description: The Medic may use this ability on any unit to remove harmful effects such as Lockdown, Optic Flares, Irradiate, Devourer Acid Spores, Plague, Ensnare and Parasites (does not affect Stasis Field).
Rating: C-
Commentary: While restoration does have it’s uses, it’s not very practical and not used very often.

Used By: Medic
Energy Cost: 75
Description: The sight range of the targeted unit is permanently reduced to 1 matrix, unless the condition is Restored by a Medic. This also removes any detection ability that unit may possess. The affected unit will display a ‘Blinded’ tag in its information box when selected.
Rating: D
Commentary: In my opinion, the worst spell in the game. Optical Flare isn’t exactly good for blinding attack units, but it can work well against detectors.

Used By: Ghost
Energy Cost: 100
Description: Lockdown Targets mechanical units shorting out circuitry of target, rendering it immobile for about 60 seconds. The Locked down unit cannot be controlled in any way. You also cannot use any of their special abilities if that particular unit has any. You can repair Terran locked down units.
Rating: B+
Commentary: Lockdown is really helpful for freezing enemy units, but requires good micromanagement.

Used By: Battlecruiser
Energy Cost: 150
Description: The Yamato Gun allows the Battlecruiser to fire a 260 damaging burst on the enemy. The energy cost of firing the Yamato gun is 150. The Colossus Reactor increases the energy limit to 250 which is very necessary when using the Yamato cannon.
Rating: A-
Commentary: Yamato Gun has a farther range than the Battlecruiser’s normal attack, making it effective in taking out defense towers and tough units.

Used By: Science Vessel
Energy Cost: 100
Description: Gives 250 pt non-regenerating shield to target unit. After about 30 seconds, the effect wears off even if the shields haven’t run out of HP.
Rating: B-
Commentary: Useful for giving your army the upper hand in battle. Also helps protect your Ghost when nuking.

Used By: Science Vessel
Energy Cost: 100
Description: The Science Vessel can fire an EMP missile. This missile has a fairly short range an affects an area. Upon impact, the shields of any units (Protoss) are dispersed bringing them to 0. The energy of any unit caught within the EMP blast is also set to 0.
Rating: A
Commentary: Excellent against Protoss, especially Archons. Will severely weaken a Protoss army or defense. Also good against spell casters and cloaked Wraiths.

Used By: Science Vessel
Energy Cost: 75
Description: Target unit becomes radioactive for 30 seconds. All air and ground units within 2 matrices of affected unit receive up to 250 hit points of damage including the affected unit itself. You can target any unit but only organic units will receive damage.
Rating: A-
Commentary: Excellent against Zerg. Can really hurt groups of units like Lurkers and Overlords. Also good against workers.

Used By: Queen
Energy Cost: 75
Description: The Queen can produce and attach a remora-like Parasite to any other unit, organic or not. These parasites give their Queen the ability to see everything the affected unit can see. These Parasites, once attached, are difficult to remove and can be destroyed either by killing the host unit or having a Medic use her Restoration ability on the host unit. Zerg Drones that have been Parasited can destroy the Parasite by morphing into a structure. In any other situation, the Parasite will survive for as long as the host unit is alive and will continue to share the affected unit’s vision with the Queen. Note that this ability works only with units — buildings of any kind cannot be Parasited.
Rating: B+
Commentary: A good spell that can force your opponent to kill the victim. You can also parasite detectors and they will detect all cloaked/burrowed units.

Used By: Queen
Energy Cost: 75
Description: When a Queen uses its Ensnare ability, a web of sticky green fluid is ejected over a small area, affecting all units caught beneath it. The affected area covers a 4×4 matrix and lasts for approximately 40 seconds. Once a unit is caught by an Ensnare, its movement is cut in half. Note that this ability is indiscriminate in its effects and you can potentially get your own units caught.
Rating: B-
Commentary: This can be used to weaken enemy forces and reveal cloaked units.

Used By: Queen
Energy Cost: 150
Description: Once evolved with the ability, Queens can launch a small spore cluster to a target non-robotic ground unit. The spores then attempt to fertilize within any organic matter in the target, even making their way through armored shells to reach their organic destination. The spores metabolize the victim immediately and within a few seconds, the spores gestate and produce a pair of Broodlings which, upon an explosive birth, destroy the host.
Rating: A-
Commentary: Spawn Broodling is great for destroying Templars, workers, and tough ground units.

Used By: Defiler
Energy Cost: 100
Description: The Dark Swarm covers a 6×6 matrix area and lasts approximately 60 seconds. Ground units within the cloud cannot be hit by ranged attacks from either ground or air, however this will not stop melee attacks or splash damage from affecting the units inside the Dark Swarm. Note that while ranged attacks will not affect units within the cloud, ranged attacks from units inside the cloud can still hit units outside of the cloud. Also, ranged attacks from units within the cloud will not work against other units inside of the Dark Swarm.
Rating: A+
Commentary: An awesome spell! Can protect your ground units during battle and with consume, it can be used over and over again.

Used By: Defiler
Energy Cost: 150
Description: Once evolved, the Defiler has the ability to produce and project a batch of corrosive spores that quickly corrodes and destroys anything caught within its effects. Plague is indiscriminate in its effects and can seriously damage both units and structures, friendly or not. Once the corrosion process begins, Plague will cause 25 points of damage per second to each affected unit. After Plague has run its course, an affected unit will have taken 300 total damage, though Plague will not cause a unit to actually die (the Plague continues, but damage from Plague stops if a unit has only 1 HP). The Terran Medic’s Restore ability is the only way to halt the course of the Plague. Note that when Protoss units are Plagued, their shields are unaffected–only their HP are reduced.
Rating: A+
Commentary: Plague has many uses. Can severely weaken enemy troops and defenses, reveal cloaked units, and when used against Terran, can burn down buildings.

Used By: High Templar
Energy Cost: 75
Description: The celestial rage of a Psionic Storm can be a terrifying sight for any unit. This physical display of the full Psionic power of the High Templar can cause massive damage, and all units caught inside the area effect of the Psionic Storm will suffer heavy damage — or possibly even be destroyed. As a Psionic Storm concentrates all the Psionic energy over a given area, overlapping Psionic Storms do not have any greater effect than a single one.
Rating: A+
Commentary: Psi Storm is one of the deadliest spells in the game. It can decimate armies, especially Zerg ones. It’s low cost of 75 energy means one templar can cast up to three Psi Storms.
Note: In 1.08, Psi Storm’s damage was nerfed from 128 to 112. Still, it’s a very good spell.

Used By: High Templar
Energy Cost: 100
Description: Hallucination creates two Illusions of any unit in the game — friendly or not — as well as Non-Player Units such as Critters. Although these doppelgangers appear to both allies and opponents just like the unit they mirror, you will always be able to distinguish your Hallucinations from your real units by their blue tint. Hallucinations are limited to the five basic functions (move, stop, attack, patrol, hold ground) and when commanded to attack, they will appear to be attacking but will inflict no damage. Hallucinations have a lifespan of approximately 180 seconds, but they take double damage from enemy attacks and disappear if an enemy uses any special abilities against them.
Rating: B
Commentary: Although not used very often, hallucination is good for making decoys in battle.

Used By: Corsair
Energy Cost: 125
Description: The Corsair can cast a web of energy on the ground that disrupts all attacks coming from within the affected area. All ground units and structures (including Photon Cannons, Spore Colonies, Sunken Colonies, Missile Turrets and Bunkers) cannot attack while within the area of effect of the Disruption Web.
Rating: A
Commentary: Very useful for nullifying enemy ground troops and defenses. However, it doesn’t last very long and has a pretty small range.

Used By: Arbiter
Energy Cost: 150
Description: The Recall ability opens a 5×5 matrix wormhole which teleports the units (both ground and air), in the area of effect to the casting Arbiter. The ability only affects yours or your teammate’s units (in Team Games) but not allied units (in Allied or Melee Games). One interesting property of Recall is that it is not restricted to only Protoss units. If you have Mind Controlled units from your enemies, whether they’re Zerg or Terran, or if your teammate has chosen either Zerg or Terran as their race, your Arbiters can Recall those units as well. Example: You can recall a group of your Zealots and High Templar, Mind Controlled Siege Tanks and your teammate’s Guardians all in one cast (if they can all fit within the 5×5 matrix area).
Rating: B+
Commentary: Good for making sneak attacks or bailing your units out of someone’s base. Kinda high casting cost though.

Used By: Arbiter
Energy Cost: 100
Description: When used, all units within a 3×3 matrix radius around the point of casting are trapped within a Stasis Field. While trapped, the units cannot be damaged, move, attack, or use special abilities. It lasts for a duration of about 40 seconds.
Rating: A-
Commentary: When making an attack you can stasis field a bunch of enemy units and kill a whole lot of stuff before they “wake up”. You can also stasis field your own army if they are about to get killed, and then send in reinforcements.

Used By: Dark Archon
Energy Cost: 50
Description: Feedback is a targeted spell that when cast on a unit, that unit lose all of its mana and will take an amount of damage equal to the mana lost. Example: If a Science Vessel with 150 Energy Points is within the range of the spell and Feedback is cast on it, the Science Vessel will lose all 150 Energy Points as well as lose 150 HP instantaneously. If the unit has more Energy Points than HP when Feedback is used on it, the unit will instantly die.
Rating: C
Commentary: While it may be useful against spell casters and BattleCruisers, it requires some micromanagement and isn’t used very often.

Used By: Dark Archon
Energy Cost: 150
Description: The Dark Archon can capture any controllable unit (this excludes Spider Mines, Scarabs, Interceptors and Larvae) when this ability is used and transfer control to the owner of the Dark Archon. The ability requires 150 Energy Points and it will drain the shields from the Dark Archon when the ability is used (essentially leaving the Dark Archon defenseless and highly vulnerable to attack). Given the steep cost of its use, you should be careful in choosing which targets you capture. Note that once used, Mind Control is a permanent and irreversible effect, unless Mind Control is used to recapture the affected unit. You will always be able to tell which units you have Mind Controlled because any captured unit will be marked with your color.
Rating: B
Commentary: It does have it’s uses, but it takes a while to tech up to. Researching Mind Control, sacrificing 2 Dark Templars, and waiting for the energy to build isn’t really worth getting 1 unit. It can also be used to control two races by mindcontrolling SCVs or Drones.

Used By: Dark Archon
Energy Cost: 100
Description: Maelstrom is an area of effect (3 matrix radius, 1 matrix = 32 pixels) ability that will instantly stun (prevents the affected units from moving, attacking, or utilizing any special abilities) all organic ground or air units for 180 cycles (or ~12 seconds on Normal Game Speed). Once cast, be sure to have attack units ready to strike the frozen units as soon as possible so that you can take full advantage of the situation in the short time that the Maelstrom is in effect.
Rating: C+
Commentary: Maelstrom is good against Zerg, but it does not last very long.