There are several reasons why one would consider going to the Derelict House, but regardless of whichever one you choose, Derlict House alongside with the Palaces of King Magish will increase your Hunters of Undead Reputation.
You can get the key for the Derelict House by completing the quest on Lvl 3. The
Derelict House consists of five bosses, all of which are guaranteed to drop
green, or occasionally blue, armour or weapons every time they are killed. There
are also some stashes, which can be seen on the map. They may or may not contain loot such as elixirs, bubbly
metal, ragtikron leather, efril, rare scrolls of healing - or may contain curses
or worthless items, or even monsters.
You need to form a party to enter the Derelict House
of between 3 and 5 people. Not all the party actually needs to enter the House.
You can re-enter as many times as you wish within a 12 hour period. After that,
you can't get a new instance for 48 hours after creating the instance before.
Each door in the Derelict House is guarded by door
guards. This means that when you attempt to move into another room, you will get
attacked by a group of five monsters, exception being the very first door, where there are only 4 monsters. To make your way through the house you can refer to the map, found in Instance Maps under Maps button on top.
To access the locations past Galmakhar you need to pull a lever that is located in the room with Revrat. Killing Revrat is possible, but not necessary.
Skeleton Wraith  - 568 HP
Revenant  - 631 HP
Revenant  - 700 HP.
In locations you will find 3 monsters of the same level as the guards. These can either join your fight, or attack you while you are standing in location, or not do either.
Resurrected Seleton  - 700 HP
Vampire  - 751 HP
Vampire  - 1200 HP
Bosses and Drops:
Each boss has a 100% droprate of a specific piece of armor - the only thing left to chance is the set from which it will be. Items have 30% durability and transferable only via party backpack.
|Phantom Corpse - 1818 HP||Cuisses|
|Revrat - 2018 HP||Cuirass|
|Galmakhar - 2331 HP||Weapons|
|Zemerkh - 2581 HP||Boots|
|Lingraonts - 4497 HP||Pauldrons|
Lingraonts also drops 5 efril to each person in the fight. Galmakhar and Lingraonts drop a helmet and crown respectively. Those can be used for quests, or broken to receive 1 additional efril for each.
The first three stash rooms have 2 Necrasphodel flowers growing in them.