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Outraged at the fall of Aiur to the zerg, some of the Khalai adopted the ways of the Nerazim and returned to Aiur to wage a secret guerrilla war. Due to their small numbers, they employed warp technology to save themselves from death on the battlefield so they could fight another day. The Daelaam led by Artanis later made contact with them again and brought them back into the fold as cloaked warriors.
The avenger is the Khalai variant of the dark templar, alongside the Nerazim dark templar and the Tal'darim blood hunter. The avenger is statistically identical to the base dark templar, and has the passive ability emergency recall. Upon taking fatal damage, avengers will recall themselves to a dark shrine under the player's control and restore themselves to full shields and health. This makes the avenger much more economical than the other dark templar variants, critical if the player is tight on resources. Their emergency recall has a lengthy cooldown, however, so the player should not deploy them again immediately and let the cooldown wear off.
The player must be sure their dark shrine is protected when using avengers, as if they do not control a dark shrine, or if they do but it is not powered, the avenger's recall will not activate. If the player controls multiple dark shrines, the avenger will recall to whichever is closest to their location.
This unit is permanently cloaked. They cannot be seen or directly attacked by enemy forces, unless they have detector support.