Sentry Ward, commonly called "sentry" or "blue ward" in the game, is a consumable item from the Dota 2 shop. A player places it at a chosen point on the map, and for a limited time the ward becomes a permanent source of detection: it reveals invisible heroes, invisible units, and enemy Observer Wards.
How a sentry differs from a regular ward
Observer Ward ("observer," "yellow ward") provides vision, that is, sight: the team sees the territory around the ward and everyone who enters it. Sentry Ward does not provide vision. It exists only for detection, the ability to see what is normally hidden. That is why the two items solve different problems and, as a rule, are used as a pair in the game.
An enemy Observer Ward that falls within a sentry's range becomes visible and can be attacked. This is exactly how teams "sweep" the enemy's vision setup: they place their own sentry next to a suspicious spot and destroy the detected wards.
How the word is used
Players use phrases like these:
- "put a sentry on the rune" — a request to cover an area of the map against invisible heroes or enemy vision;
- "we swept the wards with sentries" — the team cleared the map of enemy vision;
- "need a sentry in the stack" — the item is bought in advance, while there is money and an inventory slot, rather than at the moment when an invisible hero has already shown up for the fight;
- "buy a sentry" — a typical teammate call when the enemy has invisible heroes.
Sentries are bought and placed mostly by supports: it is one of their daily tasks alongside placing vision.
A typical in-game situation
The team notices that the opponents have a hero who can turn invisible before attacking. The supports buy several extra sentries and place them on the approaches to their lanes and around key points. Now, when the invisible hero approaches, he can be seen and answered. At the same time, a sentry helps remove enemy vision from the jungle area, in order to prepare a safe movement or a gank.
What a beginner should know
A sentry is a consumable, so it works for a limited time and does not replace other means of detection: some heroes and items have their own ways of revealing invisible units. But the sentry remains the most accessible and cheapest of them and suits any hero with access to the shop. You should cover not the whole screen with it, but the places where an invisible hero is most likely to appear or where the enemy hides their vision: approaches to lanes, jungle paths, the area near the rune, and key passages.
The term lives in Russian-language Dota 2 in exactly the form every experienced player knows: the word "sentry" without "ward" is understood by everyone, while a regular ward has its own separate name, "observer."