Starcraft 2 Sentry tactics are essential for any Protoss player who wants to utilize these units to their fullest potential. Many gaming enthusiasts make the mistake of assuming that one spell-caster is the same as another, and this often leads to some surprisingly disappointing results. Protoss players who fail to understand Sentries and how they can best be utilized are destined for failure.
Sentries are one of the rare spell-casters which can be obtained near the beginning of any game. All that is required is for the Protoss player to have constructed their Gateway and Cybernetics Core. Unlike many other early game units, this unit has abilities that remain quite useful throughout the course of any game, making it a perfect addition to any Protoss army's overall strategic plan.
The spells that Sentries are able to cast can benefit the player in many ways. Force Field and Guardian Shield are not only powerful capabilities, but are also essential for many of the Protoss' most powerful strategies. The units can also cast Hallucination once researched, which can be an effective way to scout, disrupt, and misdirect any enemy.
High Templars and other spell-casters might not have direct attack abilities, but the Sentry has no such weakness. They can target enemies on the ground or in the air. Players will quickly learn, however, that these attacks do only minimal damage. As a result, most strategies that utilize Sentries have them paired with other combat forces that are capable of providing real damage. This allows Sentries to play a supporting role on the battlefield.
Strategies that utilize Sentry abilities almost always revolve around their Force Field and Guardian Shield spells. For instance, Force Fields are commonly used by Protoss players to take effective control of various choke points on the map. Several Sentries can take turns casting this spell and block enemy units from passing through these points almost indefinitely. Only heavy units can manage to break this blockade.
Guardian Shield allows Protoss players to reduce the damage suffered by any group of friendly units surrounding the Sentries. As a result, opponents who notice that their damage has been reduced by the presence of Sentries will almost always redirect their attacks to target the Shield-producers. Savvy Protoss commanders can use this fact to bait opponents into various trap situations.
In many common Protoss strategies, Force Field ends up being a vital tool for controlling enemy movements. In the face of an enemy rush, the Protoss defender can use this capability to choke off a portion of the opposing force and cut it off from the rest of its army. This divided force can then be more easily attacked by the Protoss' own defenders. Alternatively, the Protoss player can use this capability to seal of his own army and protect it from swarming enemy units.
Protoss commanders can limit their own vulnerabilities when they understand how to best utilize the diverse capabilities of their Sentries at every stage of the game. That's why most serious players of the Protoss make an effort to obtain as much information about Starcraft 2 Sentry tactics as they possibly can.