The sentry is the first real threat in the game and the simplest one. It never moves, never turns its head to follow you, never gives chase. All it does is look — but step into what it is looking at and the road ends there.
Behaviour
A sentry stands on a fixed node and faces a fixed direction. Along that direction it follows an edge chain: from its own node to its neighbour, then on to whichever edge continues in the same direction. The chain breaks at a sight blocker, at a corner, or at a closed door.
Every node in that chain is under watch, and a sentry's sight is lethal. If you are standing on one of them when the enemy phase ends, you are caught.
From act two onward there is a rotating variant: on each enemy phase it turns to the next direction in its list, cycling back to the start. Everything else is the same — a rotating sentry still never walks.
When the sound of a bell stone pulls a rotating sentry off its post, its rotation stops too. When it returns to its post, the rotation is not reset; it continues from the last heading seen on the board. So there is no hidden reset: the heading you saw is where it left off.
How you read it
The chain a sentry watches is painted on the board: the lantern cone falls directly across the dangerous nodes. It is not an approximation — what gets painted is exactly what the engine computes.
The rotating variant carries direction arrows on its base, and the heading it will face next turn is shown in advance as a broken ring. When the threat highlight is on, that next line of sight is painted as well. So you never have to wait to see the rotation.
In act one the threat highlight is on by default: the line of sight is already painted before you make your first move.
Taught in
Taught in1-12-1
The first introduces the static sentry, the second the rotating variant. Both teach the rule with the board rather than with text: a one-line hint appears before the first move and disappears after it; if you forget, you can bring it back from "Rule cards" in the settings. Pick the wrong path and you are caught — and then you undo.
What answers it
A sentry has four answers, each covered on its own page: walk around outside its line of sight, step into a hiding spot, move it off its post with a bell stone, or approach from outside the direction it is facing and then use the takedown. The bell stone is not in act one yet.