Eye of the Beholder 2 Walkthrough - The Silver Tower, Level 3
Choosing the Right Door
Going up two flights of stairs from Level 2 brings you to a corridor, so you can go either left or right. If you take the right turn, you will find a locked door that needs a bone key. Nearby is a mouth that (very indirectly) tells you to seek ou the key and warns you about the flying snakes that pervade the whole level. The snakes are poisonous, but attack slowly and are easily killed.
Taking the left turn from the stairs, you get to a small puzzle involving three doors. A clue is given on a plaque saying that "The way through three is two, not four". This is basically telling you that from the three doors (each marked "I", "II" and "III" by plaques on either side), you need to go through the one marked "II" (straight ahead). The left door is a fireball trap, while the right door harbours a gas spore. You will encounter more gas spores later in this level, so it is good to know that they explode as soon as they are hit; so the safest way to kill them is by throwing something at them.
Through door "II", you are greeted by a mouth that will spit a fireball as soon as it stops talking, and also whenever you happen to be in front of it. From the mouth, the path right leads to a dead end, so go left. Here you come to two doors. One of the doors can be forced open, and here you will find 2 pieces of rotten food. Pick one up if you don't have any, as you will need it later.
Go through the other door. One of the flying snakes here drops a dark moon key. Now you can either go left or straight ahead.
Take the west turn and you will see a vision telling you to "choose the right door", at a point where you have to go either left or right. This is a play on words, and the correct way is to the right. If you take the left door, you get scolded and the whole party takes damage. However, either way, you get a bone key.
Back at the intersection, go straight ahead this time. You will notice a sealed door to your left (i.e. there is no button, keyhole or any other visible way of opening it). You will come back here later.
The room at the end of the corridor has a gas spore and several flying snakes, but it also has a niche with a cleric scroll of raise dead and 5 potions of cure poison at the far end of the room.
On the north wall (i.e. to the right) is a secret button that reveals a small room. This room contains leather boots, the -2 cursed polearm "Leech", +2 banded armour, and a +3 curved short sword. You probably don't want to miss out on these last two items.
Beyond the Bone Door
Go back to the bone-locked door at the other side of the level and open it using the bone key you got by "choos[ing] the right door". Here, you can go either left or right, but both ways are connected. A flying snake here drops a ring of adornment (I have no clue what it does). There are several places to visit in this area so I'll go over them briefly.
There is a passage that never seems to end. Look for a brick on the lower part on the north wall. After pushing it, you will reach the end of the passage, but you need to be careful about the spinner there. There is a niche with a potion of vitality here.
There are a couple of doors that you can open right away. One room gives you a mage scroll of disintegrate, and the other contains a flying snake that drops a dark moon key. Since disintegrate is a Level 6 spell that you will need later, and your mage(s) won't necessarily reach Level 12 by the end of the game, don't scribe it until you really do get to Level 12. You will, however, find another mage scroll of disintegrate later in this level.
At the end of a winding passage you will find a cleric who failed the Test of the Cloth and who urges you to leave. Listen to him; if you kill him, you get trapped and there is no way out. Behind him are 3 glass spheres, a +2 plate mail, a potion of healing, a helmet and a shield.
On the way to the cleric there is a turning that leads nowhere (it's a 1x1-tile alcove). Behind this alcove is an illusionary wall leading to a niche that will transform any item you put in it into a rock. You need five rocks for the next puzzle, so use it if you need to.
There is a place with four gas spores. Remember their nature and throw things at them to take them down at a distance.
Finally, there are two locked doors, each requiring a dark moon key. In one of them you'll find a potion of extra healing, a composite bow, and 5 +1 arrows. There is also a map (parchment) showing a set of illusionary walls in the next level. The other locked door leads to the mouths puzzle (next section).
The Mouths Puzzle
The final puzzle for this level involves several mouths saying riddles, and you need to feed them what they want.
The one speaking of "items born of greed" wants five rocks. The riddle is a reference to the plaque beside the niche that transforms items into rocks.
The one wanting "one's refuse" must be fed with rotten food. Skip the one asking for "nature's beauty" since you don't yet have what it wants.
The item "with the hidden glow" is the mantis idol you got from level 1. Once you feed the correct mouth with it, the mouth declares that it is "the keeper of the gate", and the sealed door you encountered earlier will open.
At this point you need to take a trip to the other side of the level to the door that was sealed, and get the red gem from there. Then come all the way back to the mouths and feed it to the one asking for "nature's beauty".
The mouth requiring "the blade which has eaten so much" wants the cursed "Hunger" that you picked up in level 1. Near this mouth, a party member will comment about the nearby walls. Attack the west wall, and the walls in front of and behind you will disappear, unleashing flying snakes at you from both sides. Here you get a second mage scroll of disintegrate.
There is a mouth that is closed and doesn't need anything. The purpose of this mouth is to reopen the door if you ever come back after finishing the Silver Tower - the second and third images above show what happens during such a return trip.
Another mouth wants something "no matter how parched". This one wants paper, whether it is a scroll or a parchment.
The final mouth clearly asks for "liquid", so give it a potion. This opens the door at the end of the corridor.
Beyond this door, you meet Dran for the first time. He introduces himself and seals the door behind you, leaving you no option but to take the stairs in front of you and go up to Level 4.