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Detectors are units or buildings that are capable of detecting hidden/cloaked enemy units. Most units and buildings do not have detector capabilities, and thus cannot sense or respond to units that are hidden, such as Spies or stationary scout units. However, Spies, Scouts, and Lookout towers can detect hidden units, as well as reveal hidden units to other non-detectors.

The following units and structures reveal hidden and cloaked units within their line of sight, regardless of their domain:

Detectors as anti-spy defenses[]

Spies are almost always cloaked, whether they are moving or stationary. Therefore, spies can move about the map unseen and invulernable. Spies are generally only forced to reveal themselves after they successfully destroy a Spy or bribe an enemy unit. However, they will re-cloak after a short period of time. As a consequence, enemy spies can be an extreme nuisance to players without detector units.

Detectors (Scouts, or Lookouts) can reveal enemy spies to your own military units and defense buildings, making them vulnerable to your attacks. Thus, it is good strategy to always bring a couple of Scouts along with an invading army, in order to reveal enemy spies and lower the chances that friendly units may be sniped, sabotaged, or bribed.

As a corollary, it is wise to make sure that your own spies give detector units a wide berth, otherwise they will be vulnerable to enemy attack.

Detectors as anti-scout defenses[]

Scouts can hide themselves from view if they remain stationary for more than five seconds. Thus, they can serve as invulnerable spy stations from which to view enemy activity. Stationary scout units can be revealed by detectors, at which point, they are no longer safe from attack.