Helmite Ghost

The Helmite Ghost is encountered during Baldur's Gate II: Enhanced Edition or Baldur's Gate II: Throne of Bhaal.
He can be found on the Watcher's Keep Final Seal dungeon level, which is part of the Watcher's Keep adventure.
This creature is essential to the Watcher's Keep plot and necessary to advance the Unlocking the Final Seal questline.
The creature can't be harmed under normal gameplay conditions and will never turn hostile. If somehow the creature is destroyed (through cheats/exploits, console commands etc.), the player's storyline will be shuttered, and the plot broken.
There are a total of four different creature files named "Helmite Ghost" used to deliver dialogue and animation in different sections/locations of the adventure. 
==Gameplay==
When the party decides to move towards the southern section of the area map, you'll observe a set of closed metallic door gates. 
Open the double doored gate, and the Helmite Ghost will initiate dialogue with the party, appearing as a wispy and translucent "air elemental". The ghost will be able to do this even if the party is hidden/invisible.
The party is allowed to reply or ask questions after the initial greeting from the ghost, who will then address those words.
If the party asks about the Imprisoned One, the ghost replies:
:I am the Keeper of the Key, the One Left Behind. Duty compels me to remain, to stand guard over one of the keys to the final seal.
If the party says, "That sounds rather ominous", the ghost retorts:
:The trials ahead are not for the reluctant. If you are unwilling or unsure, you must not attempt these tests. Return when you are ready to face the challenge.
If the party threatens the ghost, it will say:
:You cannot harm me—my spirit is eternally bound to this place by devotion and duty. Speak with me again when you are ready to face the tests of the gauntlet.
If the party states "I am prepared for whatever lies ahead", the ghost says:
:You must be worthy in heart, spirit, and mind before the final seal will be unlocked. My solemn task is to test the perseverance, courage, and wisdom of your heart.
At this time the player's Journal registers a quest, stating:
:Journal entry - Unlocking the Final Seal: I will have to prove myself worthy in mind, heart, and spirit before I can unlock the final seal, which guards the stairs to the next level of the dungeon.
The ghost continues:
:Behind me are three doors. I may not speak of the gauntlet of ordeals which lay beyond. Complete all three challenges and return to me here—only then will your heart be proved worthy.
The party must open and enter through each gate behind the ghost when they are ready to do. They may be entered in whichever order is desired. Once the party enters, they may not return until the challenge is resolved. 
After a challenge room is finished, the party may speak with the Helmite Ghost, (but it isn't required until all three are completed). It may say:
:Your task is begun, but far from over. You must complete the challenge beyond each door before the worth of your heart is beyond doubt.
When all three challenge rooms are finished, the ghost concludes the challenges by saying:
:You have completed the challenges of the gauntlet and proved your heart is worthy to face the Imprisoned One. The key to the final seal is yours.
The party will receive the Heart Key and another journal entry is registered:
:Journal entry - Unlocking the Final Seal: By running the gauntlet, I have proven my perseverance, my courage, and the wisdom of my heart. However, I suspect I must possess all three keys—heart, mind, and spirit—before the final seal can be unlocked.
==The challenge rooms==
The three gates stand before the party. In terms of which gate to choose, that is up to the player, but there aren't any indications given as to what lies ahead when transitioning through any of them. 
If the player wishes to read ahead, which is obviously a spoiler, then below are links to those challenges:
* Southwestern most gate (As viewed by the player's game screen, this is the gate to the viewers left of the central gate) - Challenge Link
* Central gate - Challenge Link
* Northwestern gate (As viewed by the player's game screen, this is the gate to the viewers right of the central gate) - Challenge Link
==Notes==
The party will probably encounter the Helmite Ghost in each challenge room after the particular challenge is resolved successfully - quest experience points are awarded for each challenge that is completed, as well as an additional when the Heart Key is bestowed.
==Gallery==
OG FS Helmite Ghost 1.png|The Helmite Ghost hails the party when it opens the gates to the challenge rooms.
Jaheira Helmite Ghost.png|Jaheira interjects commentary from the ghost's challenge trial requirements.
OG FS Helmite Ghost Journal Entry.png|The party has accepted the ghost's challenges, and the Unlocking the Final Seal quest is registered in the journal.
OG FS Challenge Journal Closure.png|The ghost concludes contact with the party after all the challenges are completed. The Heart Key and an experience point award is bestowed, as well as another quest journal entry.
OG FS Orc Challenge Helmite Ghost.png|After a challenge is completed the ghost appears in the specific challenge room to deliver dialogue.
Heart Key Awarded 1.png|All three challenge rooms are completed, and the party emerges from the last one - the Helmite Ghost initiates a final message.