Frost Wyrm (Warcraft III)

In ages past, the ancient Dragons who were near death flew to the land of Northrend to die. To this day there are entire Dragon graveyards that are littered with massive petrified bones and skulls. When Ner'zhul the Lich King took control of Northrend, he used his powerful magics to raise the ancient Dragon skeletons from the dead. Now the skeletal Dragons radiate cold power and think of nothing other than serving their dark master. Frost Wyrms have a cold-based breath weapon that can do shattering damage to enemies both on the ground and in the air.

Information
Frost Wyrms are one of the ultimate Undead units. Frost Wyrms are similar to Chimaeras in terms of damage, but they attack much slower and are also capable of attacking air units. Only their ground attacks cause splash damage - the air attack does not.

Frost Wyrms are a late-stage Undead unit and it can take quite a bit of work to build up to them, because an Undead economy is fairly slow at the start, along with both the Frost Wyrms and the Boneyards they come from costing a hefty amount of gold. If the player's aim is to quickly produce Frost Wyrms, it's recommended to scour the map of creep camps and quickly set up expansions to harvest additional gold. The wood generally comes from a Goblin Shredder. If necessary, defensive towers around your base and expansions can help.

Being undead blue dragons, Frost Wyrms still possess their former dragonflight's chilly breath, and units hit by them are slowed significantly in both their attack rate and movement speed. Like dragons, it also has a splash effect, though it does not work against aerial units.

Frost Wyrms may learn the Freezing Breath ability which causes their attacks to literally freeze enemy buildings. Frozen buildings act as if they are stunned - they cannot attack, and any actions it is performing is halted until thawed. One Frost Wyrm coupled with Bloodlust or Unholy Frenzy is generally enough to keep the building continually frozen. Though this doesn't make them essential building killers, as they run within defensive tower ranges and only deal magic damage, which does greatly reduced damage to buildings. They're there to keep the towers off of your units who are busy destroying them.

As a heavy aerial unit, Frost Wyrms are extremely slow despite their massive health pool. Night Elf and Undead players can use Hippogryphs and Gargoyles are generally the strongest counter, because they can deal a heavy amount of damage, have enough health to take several hits and can also hunt down any fleeing wyrms. Human players can use Dragonhawk Riders, as they can easily wrangle a Frost Wyrm down with Aerial Shackles. Orc players, unfortunately, don't have much in the way of taking Frost Wyrms down other than focused fire with Wind Riders, since it takes three Troll Batriders to kill a single Frost Wyrm.
 * Frost Wyrm Counters

On the ground, Dryads are the strongest counter due to their passive spell immunity which also makes them immune to magic-type attacks. Siege Engines are another alternative but require Endurance and Unholy Aura to catch up to them, but will greatly assist in taking out any Gargoyle escorts.

Freezing B reath (Passive)

 * When cast on a building, temporarily stops all building activities.

This upgrade is must have because it allows you to assault enemy towns and towers.