Dota 2 Observer and Sentry Wards: get vision without wasting your detection

An Observer Ward helps your team see an area; a Sentry Ward reveals invisible units and wards within its detection area. They solve different problems. A Sentry alone is not a reliable substitute for normal vision: to attack a revealed enemy ward or hero, your team also needs vision of that spot.

Decide what you need to see

Before placing an Observer, name the decision it supports: see an approach to your lane, check an area before your team moves, or watch a route into an objective. A ward deep in enemy territory is not automatically better if nobody can use the information or reach it safely. Look at your team's existing vision to avoid duplicating coverage.

At the shop, check the current price, shared stock and item tooltip. Observer and Sentry values can change with patches; do not spend your last support gold on a Sentry without knowing what you intend to detect.

Deward in a safe sequence

1. Suspect a ward because the opponent repeatedly reacts to movement or because a contested approach is normally watched; this is a clue, not proof of a specific location.
2. Make sure you have normal vision of the suspected ground, perhaps from a nearby allied unit or Observer. Avoid walking alone into enemy vision to place detection.
3. Place a Sentry so its detection area covers the suspected spot. If an enemy ward appears and your team can see it, attack it; if none appears, do not assume the whole area is clear outside that detection area.
4. Tell teammates what you checked and protect the route while they move. The enemy may replace a ward later.

Sentries can also reveal an invisible hero, but detection does not make an exposed support safe. Carry the detection appropriate to your role and matchup, and coordinate before placing it near a dangerous fight.

Avoid blocking your own camp

To check a camp boundary, select a ward for placement: the game can display neutral camp spawn boxes while you aim. If you want the camp to spawn, place the ward outside the box; cancel placement if the spot is unsafe.

When placing a ward near a neutral camp, watch the in-game placement indicators and keep it outside the camp's spawn area if you want that camp to respawn. If your team deliberately blocks a camp, agree on the purpose first. Patch 7.40 also added a short restriction on placing same-type allied wards very close together, so avoid double-clicking the same spot with a teammate.

Sources: Liquipedia: Observer Ward · Liquipedia: Sentry Ward · Valve: patch 7.40 · Liquipedia: March 24, 2016 patch