The Blackrock Scouts were a part of the Blackrock clan stationed on the Alterac Mountains. They appeared on the mission "Blackrock & Roll, Too!" of the Warcraft III: Reign of Chaos Undead campaign, Path of the Damned, residing in the left part of the map.
Although the orc blademaster Khanzo guarded the Blackrock Scouts' main base (see screenshot to the right), the orc force also possessed an attacking group which would strike the main player's base shortly after the beginning of the mission. Those attacking orcs, led by Haomarush, were colored teal and not blue (like the base seen in the screenshot), but they also belonged to a player with the name "Blackrock Scouts" (Blizzard most likely created two separate players to avoid AI issues). Haomarush was higher level than Khanzo, which could mean that Haomarush was the actual leader of the Blackrock Scouts.
Blackrock Scouts and the mission objectives
The main player's forces consisted of death knight prince Arthas and the archlich Kel'Thuzad, as well as their undead minions. Even though defeating the Blackrock Scouts was optional, the Blackrock Scouts would constantly send attacks to the undead base, making it hard for the player to focus on the Blackrock Warlocks guarding a Demon Gate which Kel'Thuzad needed in order to communicate with the demon lord Archimonde (the main, victory-granting quest of the mission).
Defeating the Blackrock Scouts not only stopped their attacks on the left side of Arthas's base but also granted the undead forces a tome for either Arthas or Kel'Thuzad (dropped by Khanzo when killed) and a new Gold Mine from which to harvest gold.
Forces and attacks
The Blackrock Scouts was the weakest of the five groups of the Blackrock clan, and was the only one not to have a special unit available for training. Their attacking groups consisted of grunts, troll headhunters and catapults. Khanzo would not make part of those groups, remaining at the base instead. The AI-controlled player also had, of course, peons, in order to mine gold, harvest lumber, repair damaged structures or build new ones.
Like every AI-controlled enemy player in Warcraft III's campaigns, the Blackrock Scouts did not run out of resources and rebuilt their base as long as any of their peons were alive.