As soon as Alundra enters Tarn Manor, Melzas appears, after briefly threatening Alundra, he disappears, locking the doors and sending four Murgg to attack Alundra. Once these are defeated, two of the doors open. Head through the middle door first, it contains four Murgg, once they are defeated, a chest drops which contains a Strength Tonic.
Head out of this room, up the stairs, and then up the right staircase, walk down the passageway and open the chest which contains Herbs. After that, head back down and take the left door, hitting the lever to open a secret passageway, head through it. Head down the stairs and kill the two Slimes to open the barrier. Run past the rock filled passageway in order to dodge them, in the next part of the room, hit the left lever first, and then the right one, then cross the bridge.
In the next part, the switch is pressure based, meaning that a barrel has to be placed on it in order to get past the gate, this same puzzle is repeated in the next room, except there are four barrels and four switches, make sure to kill the slimes and trigger the spiked balls beforehand, because if Alundra takes damage while holding an item, the item will be destroyed. The two chests past this gate contain some Herbs and a Gilded Falcon.
In the next room, hit the lever and go through the raised gate, either dodging or killing the slimes. The next room contains a four way switch, hit it once in order to gain access to the middle door, enter this door. Once inside the room, head towards the left wall and sprint forwards, the spiked ball should land harmlessly behind Alundra, climb up the ladder and pick up the herbs in the chest. In order to get out safely, use the holes in the wall to dodge the spiked ball.
This time, hit the four way switch three times to open the rightmost gate and head through it. In this room, step on the four switches, with one in each corner of the room, being careful to dodge the spiked balls. The small spiked balls can be jumped over if it seems Alundra is going to get hit. Once all four switches have been stepped on, the platform in the center will drop, allowing the chest containing a key to be reached. Exit via the ladder at the top-left corner of the room.
The chest in this room contains a Life Vessel, after getting it, the door at the bottom opens, exit through it. Head up the staircase and then exit up the left staircase, dodge or kill the Murgg here and enter the locked door. The left chest in this room contains Herbs, while the right contains 30 Gilder, after that, pick up the Book of Elna on the table.
Before leaving the room, Melzas will briefly appear, after he does, leave the room and then exit the Manor, return to Inoa (heading North, West, West and then South). Enter Meade's House and events will play themselves out, ending with Alundra entering Wendell's Nightmare.