The Forgotten Tower is the fourth quest in Act I: The Sightless Eye of Diablo II. This quest is different from the other quests in Act I when it comes in hunting D2 Items; it is activated by reading a book rather than by talking to an NPC. The book is known as the Moldy Tome, can be found on a stone pedestal in Stony Field. The book relays the story of a ruined castle in the wilderness that was once inhabited by a wealthy, yet evil Countess.
Getting Started in the Quest for D2 Items
To get to the quest look for the Tower this is located in the Black Marsh, beyond the Dark Wood. There are five descending floors within the Tower Cellar, with the fifth floor leading to the Countess herself. Upon her defeat, a sealed chest will open, and spew out the treasure that is the reward for this quest. In addition to a substantial amount of gold, the Countess might also drop one or more runes (provided the expansion has been installed).
The forgotten tower can be revisited any time, and it is a good place to level-up hirelings if being played in Lord of Destruction. Remember that the treasure chest only opens when the player is on the quest.
Common Strategy in Getting Diablo 2 Items
The first four floors should be treated like any other dungeon. The Countess herself is a tough, fire-oriented melee boss with several corrupted rogue minions. She stays in her room and casts fire walls on the only two entrances of the room she is in. Her minions can however be easily pulled out of the room to be dealt with individually. After taking care of her entourage the countess can be taken down quite easily.
In heavy grinding in dungeons or monsters there are instances that they drop useful items. By heavy grinding you can gain Exp for leveling purposes, gold drops for purchasing or saving money to buy some item which is more useful and item drops which can be used for crafting, gold profits in selling Diablo 2 items or profits in items in trading them to players who needs the item.