Sentry

The sentry is a protoss support unit introduced in StarCraft II available early in the game. It was previously known as the disruptor, and nullifier before that.

Overview
The sentry was seemingly designed by the Dark Templar.

Game Unit
The sentry has a beam which does continuous damage to one target.

Sentries are strong against mutalisks, and weak against hellions, stalkers, and zerglings.

Abilities

 * For the terran-devised force field, see force field (terran).

Force Field
Sentries can use Force Field to isolate enemy workers, preventing them from escaping their onslaught. Force Field also proves to be very effective for splitting forces or preventing them from passing through choke points.

Guardian Shield
Guardian Shield is most effective against attackers with low base damage: s and mutalisks. Guardian Shield protects all ground and air units positioned over the horizontal circumference of the shield (where the shield joins the ground), even if a protected air unit is not visually within the "bubble" of the shield.

The table shows the effective health for a defender protected by Guardian Shield. The figure assumes the defender has 1 base armor (as is the case with most protoss units), and defender and attacker both have 1 defense and attack upgrade. For example, the defender lasts 66% longer against marines if protected by guardian shield.

The comparisons vary only 0-2% assuming attack and defense upgrade levels remain evenly matched.

The Guardian Shield bonus is applied after the immortal's Hardened Shield. Therefore, effective health of an immortal protected by Guardian Shield is at least 125% (higher if the attacker deals <10 damage before the Guardian Shield bonus is applied).

Development
The sentry was previously known as the stasis orb. The Force Field and Anti-Gravity abilities were used by the high templar in earlier builds of StarCraft II. Anti-Gravity was later moved to the Phoenix.

In earlier builds, Anti-Gravity could affect destructible doodads, but this was a bug.

Sentries dealt bonus damage against biological units.

Earlier builds featured an ability called Null Void.


 * Null Void
 * Ability Cost: 50
 * Prevents any unit caught in the target area from using abilities that cost energy. It does not affect abilities such as a stalker's Blink, a carrier's Build Interceptor, a Phoenix's Overload or an SCV's Repair. Immediately upon exiting a field a unit can use its powers like normal.
 * Nullify acts as a detector, decloaking units such as ghosts and dark templar and revealing burrowed units. The ability to detect cloaked and burrowed units is currently being subjected to balance testing.
 * The effect lasts 15 seconds.

As of February 2009 the nullifier lost the Molecular Disruption ability.

Nullifier/Disruptor Development Images
==	Trivia==

As a disruptor, the sentry resembled a trilobite.

If you look closely at the profile, you can see it's the one used for the old model, since there's a tail instead of the blue sphere.