The Winnowing Hall is the first level in Hexen, the Tutorial, so to speak. Although it is part of the Seven Portals hub, you cannot return to it once you have left.
From the start of the level, go forward through the door and into a room with a barred teleporter in the center. Be aware that there are two traps in this room. One is triggered when you go near the one of two carvings of Korax's face in the south of the room. The walls will spin around and shoot lava balls; there are flechettes to grab on the triggers. The other trap is activated when you step onto the central platform where the teleporter is. This trap opens four chambers containing Ettins. There are also several alcoves with stained glass panels. Go into the western alcove and smash the northernmost glass panel there, revealing a hidden stairway. Go down the stairs and a switch will emerge to the player's left. Pull it and a series of four doors will slide open. Go up the passage into the next room; some of the walls will lower, revealing more Ettins. There is a switch next to the glass panels on the far side of the room. Pull it and a platform with the Emerald Key lowers. Take the key and leave the room; note that the four doors in the stairway will begin opening and closing in succession, so it is advised to run through.
Go back up the stairs and leave the building, heading southeast to a locked door. The Emerald Key unlocks it and you may proceed. There will be a button straight ahead. Push it and the stone door to the player's right will open. Go through that door and up the stairs to a rampart. Another button will appear. Push it and head back down the stairs and to the south through the newly opened door. There is a bell tower and a small cave; enter the cave and follow the path toward the Silver Key. Upon taking the Silver Key, sections of the cave passage will begin gnashing against each other; watch the timing of the crushers and run through carefully. Enter the bell tower and climb to the top of the stairs, then hit the bell: it will begin ringing. Head back to the beginning of the level and enter the teleporter room. The teleporter is now unbarred; walk into it. There will be a red portal in front of the player; walk through it to enter the first hub. There is also a passage on the right so that the player can explore the level again before leaving. Once the player enters the red portal, they cannot come back to this level.
"Winnowing" means "to eliminate that which is inferior".
All of the stained glass windows in this level can be broken, and several of them conceal items. The stained glass depicts the three character classes. Some have an extra pane above them that depicts the ultimate weapon of that class.
If the player is using the Mage class, they do not need to get the Silver Key in order to complete the level. At the area with the bell tower, aim at the bell through the window and shoot it with the Sapphire Wand to lower the teleporter in the other room.
In the first indoor room, once the ettins are released, they can be killed by triggering the Korax heads and running outside.
The player can also hide inside the small rooms that they are held in; the is a switch on the other side of the head so that they will not be trapped.
Every four minutes, between 0 and 4 ettins will be spawned, scattered throughout the map.
The map shows a hidden teleporter in the Emerald Key room. This is a deathmatch only passage, which leads to a Mystic Urn
In the room with the emerald key you can kill the ettin without getting hurt by breaking the window in the back and hiding inside.
In that same room, when playing deathmatch, there is a hidden door on the south side, behind it is a teleport leading to a Mystic Urn.
Just after using the emerald key, if you go up the steps and turn around there are stone ledges against the wall that can be jumped up to a Platinum Helm.
You can kill the ettin in the room with the silver key by standing on the opposite side of the stalagmites and hitting them. With the Fighter and Cleric classes, as long as they are within melee range, this is easy to do. However, with the Mage class, you will have to position yourself so that the wand attack goes through (there is only one spot where this can occur).