To get the preflags required, go to the sick bay in Plane of Tranquility, Hail Elder Poxbourne, then hail Adroha Jezith and say "tortured by nightmares".
Preparation: Standard melee buffs. None of the mobs in this event will cast anything. Buffing can either be done in PoN zone in area, or you have the opportunity to do so once you have been ported up into the hedges. You need an Enchanter with Memory Flux, Dazzle and Apathy memorized as a minimum. Bliss of the Nihil (AoE mez) is also useful. No wolf form should be used in Plane of Nightmare, and it is reported that Thelin Poxbourne hates charm so no charm spells should be used. Also, it is not possible to Call of The Hero across the canyon or into the Hedges.
To port to the hedges, go across the canyon and find Thelin Poxbourne by the alternative zone out. Have everyone gather close then raid and group leaders should say "I am ready" to Thelin Poxbourne:
You say, 'Hail, Thelin Poxbourne'
Thelin Poxbourne tells you, 'Who is it? Are you.. really there? You are! Please I beg of you to help me escape from this horrid place. Terris Thule is holding me here, she delights in the nightmares she sends me. To further torture me, she has offered me a pact. She has said that if I can retrieve my [dagger], then I am free to go. She does this only because she knows that I cannot retrieve it on my own.'
You say, 'what dagger?'
Thelin Poxbourne tells you, 'She has taken the only thing that has brought me any joy in my life. She took it and broke it into seven pieces. She placed them deep within the labyrinth of my nightmare. I must retrieve it, will you [help] me. Please I beg of your mercy.'
You say, 'I will help you'
Thelin Poxbourne tells you, 'I do not know who you are, but I am thankful that you have stumbled upon me. I can bring you into my dream state, but my powers are limited so I can only handle eighteen at once. Please when you are prepared have the leader of each of your band of adventurers tell me they are ready.'
You say, 'i am ready'
Thelin Poxbourne says 'Thelin Poxbourne closes his eyes and falls asleep immediately. He looks peaceful for a moment and then screams in agony!'
Your group is now ported to the Hedges zone in area. You will see Thelin Poxbourne standing there. He will not move until you talk with him, so there is an opportunity to buff and prepare here.
To start Thelin Poxbourne walking around the Hedges, say to him "I am ready":
You say, 'i am ready'
Thelin Poxbourne says 'Please stay close, I know not what horror Terris will unleash upon us.'
Thelin Poxbourne will now start to walk around the maze. There are a number of mobs in the maze that will attack him as he walks around. Mobs that will be encountered are bloodthirsty ravens, abhorrent nightstalkers, thulian nightstalkers, nightstalkers, sinister nightstalkers, dark visages and agressor arachnid's. Some are static spawns and these can be killed by having a group or 2 running a little ahead of Thelin Poxbourne. Your job is to keep him alive all the way through the maze. At various points Thelin Poxbourne will trigger the spawning of mobs. The first time there will be 1 mob, the second time 2 mobs through to the sixth time 6 mobs. These are usually in clearings, and Thelin will have walked to a corner of the clearing. Have melee types stand in the centre of the clearing as this is where the mobs will spawn. Casters should stay on the edge or stick with Thelin Poxbourne. The enchanter needs to mez Thelin Poxbourne when a fight commences to prevent him from being attacked. The mobs will summon (and summon Thelin Poxbourne) to kill him. Dazzle is sufficient to mez Thelin Poxbourne, Apathy and Bliss of the Nihil is required on the mobs. Mem blur Thelin Poxbourne as necessary. Its worth noting that Thelin Poxbourne is a caster so the enchanter can take the opportunity to use Theft of Thought on him. Triggers for spawning mobs are, in order:
Thelin Poxbourne kneels down and picks up a dagger hilt.
Thelin Poxbourne slowly picks up a shard of a dagger blade.
Thelin Poxbourne picks up a the top half of a dagger blade.
Thelin Poxbourne picks up a dagger handle with a small hole in it.
Thelin Poxbourne kneels down and picks up a dagger blade tip.
When you approach the large clearing in the centre containing a fountain, mez Thelin Poxbourne. Have the raid move on ahead and clear the area of mobs. When the area is clear, release Thelin Poxbourne and let him enter this area. When he reaches the fountain, this will trigger A construct of nightmares to spawn just in front of the fountain. This is a level 65 mob with loads of HP. Kill him and loot a Dagger Blade Shard. Once mez has worn off Thelin Poxbourne, hand him the Dagger Blade Shard. You will get Thelin's Dagger given to you (will appear in your inventory, remember to distribute this loot). This will cause Terris Thule to briefly spawn:
Thelin Poxbourne takes the final shard from you and places all of the pieces on the ground, with unseen hands the dagger moves together and fuses itself back together into one complete piece. Thelin picks it up and hands it to you.
Thelin Poxbourne says 'Terris hear me now! I have done as you have called for. My beloved dagger is whole once again! Come now keep up your part of the bargain.'
Terris Thule says 'You fool! You did not earn this prize on your own! The contract that has been drawn is now invalid. You will never leave my grasp, prepare your soul for eternal torment!'
Thelin Poxbourne says 'Vile wench, I knew in the end it would come to this. You shall pay dearly for your injustice here.'
Terris Thule laughs heartily and then vanishes in a swirl of incorporeal mist.
Terris Thule begins to cast the gate spell.
Terris Thule begins to cast a spell. <GMGate>
Now you need to make sure that all pets are killed, and then hail Thelin Poxbourne to receive a flag. Hailing Thelin Poxbourne causes him to cast a spell on you that ports you out of the hedges and this is why pets need to be killed. The pets treat this as an act of aggression and rather than be ported attack Thelin Poxbourne.
You say, 'Hail, Thelin Poxbourne'
Thelin Poxbourne tells you, 'Please destroy her for all that have had to endure her hideous visions.' Thelin closes his eyes and is swept away from his nightmare. The land of pure thought begins to vanish from around you.
You have received a character flag!
Thelin Poxbourne begins to cast a spell. <Waking Moment>
After the hedges event it is alleged you have to go back to the Sickbay in PoT and hail Elder Poxbourne and Adroha Jezith again to complete the flag.