This video demonstrates all the latest updates that have been made made to StarCraft II: Heart of the Swarm units since they were unveiled at BlizzCon last year.

Some very cool stuff in here. The Protoss units on display are the Mothership Core, the Oracle, and the Tempest. Terran gets the Battle Hellion, Warhound, and Widow Mine. Zerg get the Swarm Host, which summons endless Locusts, the Viper, which is basically the new Defiler, and the Evolved Ultralisk.

Here's Blizzard's entire run-down of all the new units and abilities; rather than attempt to summarize or cherry-pick, I thought I'd just run the entire thing:

Protoss

Upon analyzing data from their most recent battles, the protoss have identified a few areas of improvement that would help them maximize effectiveness against their enemies. Based on their findings, the protoss have augmented their arsenal with an extremely long-range attacker, additional psionic units, and a new form of enemy harassment.

Tempest
Description: The tempest is a new capital ship that can fire at both ground and air targets from long range, doing additional damage to massive units. A further range upgrade can be researched to give the Tempest the ability to fire from incredible distances.

Oracle
Description: The Oracle is a psionic warship, built from a Stargate, that uses several unique abilities to raid and harass the enemy. The first is Entomb, which can temporarily block mineral fields from being harvested. Another ability, Preordain, grants detection and vision around a targeted building, allowing the protoss to see which units or technologies are being researched. Rounding out its kit is Cloak Field, which temporarily cloaks everything around the Oracle.

Mothership Core
Description: The Mothership Core is unique in more ways than one. Only a single one can exist in your army at once and it's also immobile, attaching itself to a nexus. There are four abilities available from the Mothership Core. Teleport allows you to move the Mothership Core to any of your other nexuses. Energize tops off the energy stores of any target unit or structure. Purify is a defensive ability that temporarily grants the Mothership Core a powerful, long range attack. Finally, Mass Recall allows players to quickly recall units back to the Mothership Core.

Mothership
Description: It's not really a new unit in Heart of the Swarm, but the Mothership abilities are slightly different from Wings of Liberty. The passive cloaking field is gone, with the cloak now available as an activated ability on the Oracle. The Mothership retains its Recall ability, and the Vortex spell from Wings of Liberty now affects ground units only. A new ability called Stasis is available, which puts the mothership and all air units around it into stasis for about 20 seconds. The Mothership is now created by upgrading the Mothership Core after a Fleet Beacon is constructed.

**In the current multiplayer build of Heart of the Swarm, the protoss are not able to deploy Carriers. However, we have not yet made a final determination on the Carrier's status..

Terran

The resourceful terrans have also been improving their technology to better survive their battles in the Koprulu sector.

Widow Mine
Description: The Widow Mine is a new suicide unit built from the Factory that allows the terran player to control areas of the battlefield. The Widow Mine moves into position and sets to stationary mode, which burrows and activates it. When an enemy air or ground unit moves into range, the Widow Mine briefly flashes before moving and attaching itself to that unit. After several seconds, the mine detonates, dealing 200 damage to the unit and a smaller amount of damage to units in the surrounding area.

Warhound
Description: The Warhound is a walking ground mech that is specialized as an anti-mechanical weapon. Smaller and more nimble than a Thor, the Warhound has a standard weapon to hit ground. Its true strength is an additional ability that fires powerful missiles at ground-based mechanical units, making it particularly well suited to taking out enemy siege lines and many protoss ground units.

New Abilities
The Hellion has been upgraded to a transforming unit similar to the Viking. When constructed from the factory, the Hellion spawns in its new battle mode, which gives it additional hit points and a stronger flame attack that covers a short forward-facing arc. This makes the Hellion more effective in late-game fights against large clusters of light units such as Zealots. The player can opt to transform the Hellion into its original, more mobile form as well.
In Heart of the Swarm, the Battlecruiser gains a cooldown-based speed-boost ability called Redline Reactor. Finally, the Reaper no longer has a special building attack. Instead, it gains a passive health-regeneration upgrade that allows it to recharge hit points quickly when out of combat.

Zerg

The zerg continue to evolve and adapt to changing environments, particularly the dangers they face on the battlefield. New creatures will help the zerg stage more effective sieges and add unique enemy-manipulating abilities to their arsenal.

Viper
Description: The Viper is a new flying unit with three unique abilities. Blinding Cloud temporarily reduces the attack range of biological ground units inside the cloud to melee range. Abduct allows the Viper to physically pull a unit to the Viper's location. Finally, the Viper can use Consume, a channeled ability that allows it to gain some energy back at the expense of damage to your own zerg building.

Swarm Host
Description: The Swarm Host is a slow-moving ground unit that has no standard attack. When burrowed, the Swarm Host spawns a continuous stream of slow-moving units called Locusts that can be used to lay siege and pressure entrenched enemy positions.

New Abilities
Ultralisks have a new Burrow Charge skill that lets them dive underground and quickly surface at a target, allowing them to initiate the fight faster on a crowded battlefield. However, its "frenzy" passive from Wings of Liberty has been removed, meaning the Ultralisk can now be snared by abilities like Fungal Growth. The Overseer has been retained from Wings of Liberty, and changelings can now be spawned from siege range. Finally, the Hydralisk has a new upgrade that allows them to move faster while not on creep.