Zealot: Zealots are the standard infantry unit of the Protoss from StarCraft. Still equipped with a pair of glowing psionic blades for melee combat, the Zealot will now charge the enemy to close distances with ranged units quicker than before.
Stalker: Stalkers are a new type of dark dragoon. They're fast moving and lightly armored with a powerful anti-air and anti-infantry weapon, but their secret weapon is their “blink” ability that will allow them to teleport anywhere in visual range in an instant.
Immortal: A new type of heavy dragoon, the Immortals will be equipped with a shield that activates only when hit by heavy weapons like siege tanks, making them excellent for assaulting heavily defended positions but weak against raiding parties with light weapons.
Observer: The invisible flying eyes of the Protoss are back. We can confirm they'll be in the game, but further details are shrouded in secrecy.
Colossus: True to its name, the Colossus is an enormous four-legged walker that rakes the ground with a heavy beam weapon. They'll be extremely effective against small swarming units like Zerglings or marines—their beams target one unit at a time, and instantly sweep to a new target when the first is destroyed. Using their long legs, they can step up and down ledges with ease.
Phoenix: When its standard fighter weapons won't do the job, the Phoenix will be able to activate its overload ability to damage all enemy air units nearby, which also disables the Phoenix itself for a few moments. If the overload doesn't demolish the enemy, you'll be a sitting duck.
Phase Prism: The new Phase Prism will serve as both a troop transport and a mobile power pylon, allowing you to restore functionality to a base when your pylons are destroyed by raiders or when you build away from your base. Combined with the warp-in tech, you'll be able to use them to create an army anywhere on the battlefield.
Warp Ray: These flying weapons inflict additional damage the longer they fire on a single target as they bring more beams online, which will make them extremely powerful against large targets like Battlecruisers and structures. Their focused fire also makes them vulnerable against swarms of small anti-air units like marines.
Mothership: At the top of the tech tree, you'll find the Mothership. It comes equipped with a “time bomb” field that stops incoming projectiles, Matrix-style, in mid-air. When the field shuts off, all attacking missiles will fall harmlessly to the ground. Like any good mothership, it'll be able to fire a devastating planet cracker beam straight down to annihilate ground units below. Finally, it'll be able to generate a mini-black hole to suck enemy air units into oblivion. There's nothing quite like watching a fleet of enemy Battlecruisers circle the drain!
High Templar: The High Templar is back, and he'll bring his powerful psionic storm area attack with him. But he's gotten a handy new power: he'll be able to create a force field to trap units temporarily, or to create barriers. Blizzard says internal testing has revealed some extremely effective bottlenecks tactics using him. The ability to say, 'you can't go there anymore' will be extremely powerful.
Dark Templar: Just like in the first game, the Dark Templar is a stealth melee unit that wreaks havoc on any force foolish enough to leave home without a detector. Any new special abilities have yet to be revealed.
Twilight Archon: Blizzard hasn't exactly worked out what it's doing with the Twilight Archon in terms of his powers, but the team promises that he'll be just as powerful as he was in the original StarCraft.
Tempest: The Tempest is a dark carrier with disc fighters and a strong shield that activates only when attacked from the ground. It will have no defense whatsoever against air attacks.
Soul Hunter: Soul Hunters are anti-infantry units that float around on hoverboards and suck the souls out of enemies. The more souls they consume, the more powerful they'll get, going from firing one beam at a time up to three. They'll be effective against small organic units, but practically useless against robotic units like the Protoss' own Reaver.
Reaver: The armored slug-like Reaver artillery is as nasty as ever. While we didn't see any upgraded abilities, we witnessed a new version of the old 'reaver drop” attack (putting one right in the middle of an enemy's resource collectors and watching the fireworks) when combined with the Phase Prism.
Phase Cannon: This stationary base defense is no longer stationary. The Phase Cannon can now convert into energy form to relocate and redeploy, as long as you stay in pylon power range. But if the pylon is destroyed while the phase cannon is in energy form, it'll go poof!
Star Relic: When it comes to casting spells, the Star Relic makes the High Templar look like an amateur. It'll be able to create a cloak field that will conceal even buildings, and fire a fusion beam that slowly damages a target until it dies—and when it dies, it'll explode and cause damage to everything around it. Remember: The larger the target, the bigger the boom.