Depravity made such a nice map of the Mabar Dragon Instance that I had to write a guide to go with it. Also, since I was the one who asked for a walkthrough a week ago, I feel obliged to write one now. Here it is.
Joe Lantern the pumpkin-wearing mindflayer has summoned an undead Spectral Dragon! It is now up to you and a group of 16-24 complete strangers to take down the beast and recover the spoils. Will you be cluey, or will you be a noob?
Overview and Objectives
Protect the altars from the dragon and the Night Gargoyles. Keep the lights on to greatly weaken the enemies. And slay the dragon!
Before the quest
Prequisite item: You need an Ethereal Key to enter the instance. Keys are dropped randomly by graveyard undead just like ingredients.
Keep track of how long until the next summoning by talking to Joe Lantern about how many more ritual ingredients are needed. When it hits around 2k, you have maybe 5 minutes until the gates open. Restore your SP and HP (unlike normal quests, the quest instance is considered a public instance. So you will enter the instance with your CURRENT hp and sp). Tip for lowbies: Go to the tavern and stand near the bar. You will be hit with many high level buffs, all of which you can bring into the quest with you (but only the ones that last >10 minutes will be useful). Note: you will NOT get a notice of the door opening if you're in House J. Keep track of the time. When the gates open, enter immediately. Time is of the essence.
You have 10 minutes from the start of the instance until the Dragon appears. During these 10 minutes, all players must spread out to make sure all the vital quest locations are covered. This is the most tricky and crucial part of the quest.
Map courtesy of Depravity's map post
You will spawn in one of 4 randomly chosen corners of the map (see green stars on map above). That means other players will be randomly distributed around the corners also, so there's no need to run to the one farthest away from you. The corners are at NW, NE, SE, SW. Head straight towards either the nearest:
1. Altar Room: From the main corridor, you will have to go up a ramp marked with yellow runes, and drop down a hole. Touch the altar to activate it. To exit an altar room, you have to go to a hole in the ground (also marked with runes), drop down, run through a corridor, and climb a ladder to get back up to the main corridor room.
2. Lever Room: these are visible from the main corridor. Levers will be locked to OFF until the 10 minutes deployment time is up and the mobs start arriving. When that happens, your job is to make sure it's in the ON position and the altar room it overlooks is lit up. More on that later.
Open General Chat and keep sharp notice of it: it is now restricted to only the players in your instance. Once you're at your chosen location, announce your local headcount regularly into General Chat. E.g., if you're in the SE Altar Room, and there are 5 players there, say: "SE altar: 5"; One guy at the SW lever = "SW lever: 1". Other players should be announcing their headcounts too as more players enter the instance.
It's possible (maybe even optimal) to complete with 5 teams, one for each altar room and one roving team for all the levers. But IMO this potentially requires a very high level of coordination that you should not be expecting if you're a new player reading this guide. Most of the time, you'll have enough players that you don't have to short-man like that. So we'll assume we need 8 teams: 4 altar rooms and 4 levers.
Each lever room needs at least 1 person or you will fail (preferably at least 2 if you have more than 16 players)
Each altar room needs at least 2 people or you will fail (preferably at least 4 if you have more than 16 players)
Rearrange yourself into teams of roughly equal size in each corner. If one of the rooms or levers is not announcing a headcount for a while, assume there's nobody there. Go and check! The Phiarlan Pendant of Time, or Haste and Expeditious Retreat is very helpful for navigating through the long corridors quickly. If there are 6 or more people just hanging out in a room, someone almost certainly needs to move. If you switch rooms, announce your intentions so people don't collide, e.g., say on gen chat: "I'm moving from SE to NE".
If you need more people in your room, or if you're looking at the announced counts and it looks uneven but you can't move yourself since it would leave your room undermanned, feel free to suggest people move to the undermanned rooms.
Once everyone is in place, if you want, you can party up with the other people in the same spot so they can monitor health bars. Often you can't because they're already in a party. It doesn't matter, just make sure you're self sufficient. BYOH (bring your own healing - potions wands etc), because if you die and are not ressed in 2 minutes, you get booted and don't get a reward even if the instance wins. Cast your long lasting buffs (most of your SP should regenerate before the dragon arrives).
Things are pretty simple when the quest begins. The dragon "Eternity" spawns in one of the 4 rooms at random, fights a bit, then teleports out to another random room, repeat until he's dead.
At regular intervals Night Gargoyles will spawn in all the rooms and also rush any levers that are on: they will attempt to destroy the altar, or turn the switch to cut the lights in the altar rooms. If any altar is destroyed at any time the quest instafails. If the dragon is in a dark room, it gets much stronger, gets damage reduction, etc.
Hence your goals are, in order of priority:
1. Protect the altars
2. Keep the lights ON
3. Slay the dragon
Yup, "slay the dragon" is the lowest priority. It should just happen naturally if you're doing 1 and 2 correctly.
Levers cannot be destroyed, so if you're defending a lever over a room with no dragon, you can conserve resources and leave the lever off (which causes the gargoyles not to spawn) or take them out slowly. If the dragon is in your room though you better keep those lights ON if you want your buddies down stairs to be making progress at all.
Aggro-grabbing the night gargoyles is thus of the highest importance. Their aggro is very easy to grab, you just need to damage them a bit. For the lever teams, one should grab aggro while the other makes sure the lever keeps the lights ON.
For the altar rooms, immediately announce on gen chat when the dragon ports into your room to alert the people in the lever room. This may also alert people running around upstairs to reinforce the appropriate lever room.
I'm not sure what the stats on the mobs are, maybe other players can contribute here. All I know is Eternity can be hurt with fire (slightly resistant) and ice (not resistant) and is immune to lightning. Disintegrate works on the dragon. The gargoyles are Evil (so your Holy / PG stuff works on them). Eternity is an Undead, not a dragon, so Firewalls and cleric light spells do double damage and Dragon Bane does nothing. Eternity has a pretty weak aura of cold that damages you if you're close, so try to have some cold resist on the melees.
Once someone kills the dragon, you will get a victory message. After a few seconds, everyone will be booted from the instance, with a shiny Spectral Dragon Scale in your backpack, which you can exchange for Halloween goodies.
Happy Halloween and Good Undead Hunting!