The guardian is converted from an existing mutalisk. It has an anti-ground attack that out-ranges almost all ground-to-air weapons, and in large groups can be particularly devastating as a bomber unit. While the guardian has a respectable attack of 20 (26 when fully upgraded), it has no defense against enemy air units and is vulnerable to ground-to-air units when on the run. The slow speed of the guardian also renders it vulnerable to area-of-effect spells such as psionic storm and irradiate, or long range anti-air units.