Note: In Update #100, the Sentry gun deployable became unlocked by default (though the mechanic of requiring a skill to unlock a sentry gun was reintroduced in the Engineering skill), and the aced effects of this skill were moved to the aced version of Eco Sentry. This skill is still available on the console versions.
|Basic (1 pt): Unlocks the sentry gun for you to use.|
|Ace (3 pt): Your sentry gun gains 150% more health.|
- "Fucking Sci-fi robot guns!"
- —A law enforcer upon seeing a sentry gun.
The basic version of this skill unlocks the sentry gun for use, an automated defense turret, which can be deployed once in a heist that will function until it is destroyed or it runs out of ammunition. The aced version increases the sentry gun's health by 150%, allowing it to soak up more gunfire before failing.
Without further upgrades, the sentry gun is quite inefficient at killing enemies. It is too underpowered and too inaccurate for later levels. The basic sentry gun is useful as a distraction, as police units tend to focus on the sentry gun rather than the players when the gun is active.
Players wishing to use the sentry gun will likely need to invest a large number of skill points into its upgrades in order to make it feasible to use in combat. The various upgrades to the sentry gun are almost necessary for it to perform well on higher difficulties, as its most basic form is feeble at best.
The aced +150% HP upgrade is very invaluable in making the sentry gun into a viable distraction unit at starting levels, where later upgrades are still unavailable. While it is still valuable at the end-game, for players wishing to save on points, it is best to ignore the aced upgrade and instead invest in the aced version of Sentry Combat Upgrade for the shield upgrade, which makes the sentry gun invulnerable from the front. With careful positioning, it is very unlikely that the sentry gun will take any significant damage while it is still active, negating the use of additional health.