Taking the Mine

As the characters approach the Hardy Mine, they see the stream they have been following leading further up into the mountain canyon. On the right of the stream a squat two story tower has been fitted against the side of the cliff. There is a flickering orange light coming from the upper windows of the tower, and smoke rising out of the same windows.
Across the stream on the left bank stands the longhouse and stable. The longhouse is belching smoke from its central vent, and a terrible odor flows down from the buildings that is almost palpable. Beyond the buildings lies the dark entrance into the mine itself. There is no sign of activity in the tower other than the firelight in the window. To the left, there is no obvious movement (DC20 Perception will notice two figures blending against the sides of the cliff on either side of the mine entrance, watching the buildings, the stream, and the slope you are approaching).
If the players notice the guards, they can conceal themselves before they are noticed. Any further advance must be made with stealth checks against the orcs' passive perception of 10. If they all try to cross the open space to the buildings at once, have them roll with disadvantage.
Crossing this way, they can reach the buildings. Peeking inside, fifteen orcs are sleeping inside the longhouse. If they wish to charge in, let them. If they prefer trying to get past the guards into the mine, allow them to make a surprise attack against them, then roll initiative. If they are able to defeat the two guards in one or two rounds, they will be able to slip inside without alerting any of the sleeping orcs.
Once inside, the party can take a short rest before continuing inside. As they move down the main corridor into the mine, have them roll perception checks. On a roll greater than 15, they will hear the voices of an orc patrol nearing the intersection ahead. This will let them stay out of sight and allow the patrol to pass without noticing them. If none of them roll high enough, they will meet each other at the intersection. The patrol consists of three orcs and one orc war chief.