When the first expansion to StarCraft 2 launches, it will be bringing more than just a single-player campaign. It will also boast a number of new multiplayer changes as well.

Today Blizzard gave fans a sneak peak at the new units they're planning to intergrate into SC2's famously well-balanced online play. This doesn't necessarily mean the game is coming soon though. In fact, we don't even yet know when the beta will start. However, SC2 fans are very particular, and Blizzard wants to make sure everyone is well aware of the changes long before they're implemented.

On to the changes:

Zerg:

Units:

Swarm Host - Intended as a Zerg artillery unit, the Swarm Host continuously fires swarms of locusts at both land and air units.

Viper: This is being called a "battlefield manipulation unit" with two new abilities. The first is called Abduct and allows it to snare and draw units toward it. The second is called Blinding Cloud and creates a zero visibility environment in which range is reduced to zero.



Abilities:

Ultralisk - may now burrow underground and charge forward for quick attacks.

Hydralisk - speed boost while close to the hive, allows zerg to be more mobile.

Protoss:

Units:

Oracle - Harrassment unit which can use an ability called "entomb" to prevent enemy resources from being mined. Can cloak nearby enemies and buildings. Can also cast "preordain" on enemy or building to gain detection against cloak.

Mothership Core - Available immediately. Can transform into mothership later. Teleports to any nexus, and can use "purify" to defend base. Can also give energy to units, and recall units to the base.

Tempest - Capital ship that targets one enemy at a time unlike the Carrier. Blizz is reportedly considering an upgrade that would make its range enormous. Nearly twice the range of a siege tank.

Terran:

Units:

Battle Hellion - Can transform into either a speedy, lightweight form or a hefty tank-like form.

Warhound - Designed as an anti-vehicle unit, the warhound has two attacks: a cannon which targets anything, and missiles that automatically target vehicles. This will be the first time Blizz has used auto-target in StarCraft.

Widow mine - Burrows into the ground, then attaches itself to a passing enemy. Explodes for 200 damage + splash damage after 10 seconds. Will not explode if attached unit dies.

Abilities/Upgrades:

Reapers - No longer have bombs when targeting buildings. Instead, now reapers can recharge health when not in combat. Blizzard hopes this makes them more viable as scouts.

Battlecruiser - Experimenting with a speed boost ability. Not final.



As huge SC2 fans, we're a little nervous about the changes. We've spent the last two years learning this game backwards and forwards. New units and abilities can completely change the game. We'll have to see how these units affect play once they're finally implemented.

Once again, we're still not sure when that will be though. Blizzard said last April that Heart of the Swarm would launch in about a year. And it's been nearly 18 months. So it's anyone's guess at this point.

You can check out G4TV.com for a somewhat more complete explanation of the changes.