Zerg Swarm (formerly) Feral zerg
Scar (as named by Marshal Rin Shearon) was a canny mutalisk that lived on the moon Choss. It briefly terrorized the population before being slain. It had scarring around its mandibles, and was of an abnormally large size.
Scar was a mutalisk that survived the troubles and the subsequent purging of Choss by Terran Dominion forces. It and its spire hid in Anvil Rock and managed to survive there for years, feeding off of the range boars and game bats that were plentiful in Choss's wet season. During this time, Scar began to develop a self-preservation instinct, and began to adapt to the acid blood of it and its flock, becoming a canny mutalisk.
As the range boar and game bat population began to dry up, Scar and its flock began attacking human tourists. First to die was university football star Alden Moss, prompting an investigation into what killed him. Mayor Haskins refused to investigate fully until five more died, prompting them to contact the Terran Dominion and Raynor's Raiders. The Dominion sent a mutalisk specialist named Brad Champlain while the Raiders connected them with a mercenary named Breg Shaw. Champlain was excited for the potential existence of a mutalisk like Scar, which they could actually dissect without it dissolving itself. The two of them and Marshal Rin Shearon set out to destroy Scar and end the mutalisk problem on Choss.
They encountered packs of mutalisks who ambushed the group, but with the anti-mutalisk goliath Flyswatter I they beat them back. However, they began to get swarmed as the group approached the spire an Anvil Rock. Scar led the pack, killing Shaw with a glaive wyrm. Shearon lured the mutalisks to the top of the spire with her blood, then used a grenade to destroy the spire. The resting mutalisk's acidic blood destroyed the flock, and killed Scar. Champlain and Shearon survived, and took Scar's corpse back to town.