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The Ghostly Hero will follow the person who talks to him. To have him stop following, the same person must speak to him again. Follow the path and kill any Losaru you encounter. They come in groups of three (four groups in total: three groups of Losaru Bladehands and one group of Losaru Bowmasters). Near the Bowmasters, you will see a Siege Wurm firing at you from across the chasm (point A). Kill the group of Losaru Bowmasters first (keeping your ranged people back), then move the Ghostly Hero to the drawbridge to lower it.

South after the bridge you will encounter the boss Goss Aleessh (point B). After defeating the boss and his minions a cutscene will take place. Afterwards, move the ghost towards the raised drawbridge to the south, but keep him at a distance. Have the person he is following speak to him and he will stay put. Have any ranged attackers kill the Enchanted Bows on the ledges beside the bridge. Once they are disposed of, bring the ghost to the bridge (have a party member talk to the ghost) and he will lower it. Do not go in past the arch. Enemies will come out in pairs; just wait for them on the bridge. After the last wave (it's the group of three instead of two), defeat the ghost on the altar (point C).

At this point you should stop and tell the party to prepare themselves. If going for the bonus, now is the time to decide upon a strategy. When everyone is ready, bring your ghost near the altar to start his ritual. You will have to defend him for 10 minutes. Four pairs of Forgotten Arcanists will appear: a pair from the east, then the west, then the south, then the east again. If your party has a good amount of firepower and can eliminate enemies quickly, head out and intercept them as they come in so as to prevent them from ever threatening the ghost. On the other hand, if your party is stronger defensively, it may be better to stand your ground at the altar. This also avoids the hassle of running back and forth, though with running skills equipped this is a negligible annoyance.

After defeating them, rush to the south bridge and defeat the two incoming Enchanted Bows. Then head to the west bridge to defeat either a pair of Enchanted Hammers or a boss group. After defeating this group, run back to the altar, and simply wait it out. The last group to attack the altar will be the one you didn't fight at the west bridge. After that, no other groups will attack. The ghost will sometimes cry about incoming enemies, but there really aren't any more. However, do not forget about the remaining Siege Wurms. They will decimate your ghostly hero if he is left alone.

Note: The ghostly hero can get stuck. If this happens before a cut scene and he's in a safe spot, you'll be able to continue the mission without him, and he'll appear with you after the cut scene. If he gets stuck after the cut scene with Goss Aleessh, but before successfully opening the bridge to the fort, you'll have to start the mission over again. Attempting to talk to the stuck hero will produce messages like "We are in battle" when no battle is actually taking place. At least some of the time, this is related to the Siege Wurm, and can be solved by killing it.

Tip: Eliminating the first Siege Wurm goes a long way to ensuring the survival of the Ghostly Hero. There is a break in between the first four waves of Arcanists and the next wave of Enchanted. Take this opportunity to kill the Siege Wurm outside the eastern (left) side of the fort. With a decent amount of firepower you should be able to destroy the wurm before the Enchanted bows at the southern bridge start advancing on the Ghostly.

Tip: Before engaging the enemies at point B you could go to the west to point D. There is a group of Losaru guarding a Slow Totem there. The totem slows down enemies within the area where it is dropped. It is most useful for the bonus and can be quite helpful for the mission too if used correctly. Note that enemies under the effects of Slow Totem are not hexed with Imagined Burden, even though the animation is the same.

Tip: Unless attempting the bonus (see below), it is very important for the party to stick together at all times during the 'siege'. Arcanists and Enchanted can take quite a beating before going down, and they stack up quickly without a proper offense. The Ghostly Hero won't last more than a minute at best if under attack, and as usual his death means a mission failure. If you're using a human Monk, make sure they give priority to healing the Hero.

Tip: Interruption and skills that cause the Dazed condition are helpful in this mission. Forgotten Arcanists are most dangerous due to Earthquake and Kinetic Armor - interruption leaves them vulnerable and mostly harmless. Siege Wurm's attacks (Wurm Siege) are also spells and susceptible to interruption.

Bonus
This bonus is arguably the hardest bonus in the Crystal Desert. There are several strategies on how to complete it:

Approach 1: Finish off attackers then head out

Do exactly the same as above, but in the last part, after defeating the first set of enemies at the west bridge, head further west (towards point 2 on the map). Wait for and kill the incoming group of enemies, or they will attack the ghost while you are out attacking the generals. At this point, you should still have around 6 and a half minutes left.

Quickly head back into the fort (don't go around the outside or you will be beset by Jade Scarabs) and head south over the southern bridge. There you will see a small fort. The first general will be standing outside (point 1). Stick together and follow the path because there are Scarabs that pop out from the ground. After defeating the first boss and his group go south into the fortress. The other two bosses and their groups are found to the left and the right inside the fortress (marked with a 1). You need to defeat the bosses and their guards to complete the bonus. The Ghost needs to survive up to this point, but he can die afterwards as you have already completed the bonus. If you are also doing the mission, then run back to save the ghost.

Approach 2: Protect the Ghostly Hero

A different approach is to split up the party. For example, a single bonder using Life Bond, Life Barrier, Mending and Watchful Spirit is able to keep the Ghostly Hero alive throughout the whole attack, so that the remaining five players can go for the bonus without having to worry about him.

Due to an update, the Ghostly Hero will now take much more damage than before. Even with +7 health regen (by also using Succor) and 52% Life Bond (48% damage from spells, 24% damage from attacks), the Ghostly Hero will need healing attention every 30 to 60 seconds after 5-6 minutes has elapsed (depending on Boss spawned to attack him). Healing Seed is a good healing spell to cast on the Ghost, then run back to the bridge.
It is a good idea to also put Mending and Watchful Spirit on yourself once the Ghost starts taking hits (since you will need to briefly move into aggro to cast Healing Seed). This will put you at -8 energy regen from maintained enchantments, but there will not be an energy management concern as the Ghost takes many attack hits per second. Killing the first 2, 4, or even 6 Forgotten Arcanists that attack him will make the Ghost take much less damage (as he has less damage reduction from spells).
Attribute points for this method are 13 Healing, 16 Prot, 13 Divine (using 3 superior runes on appropriate head armor, switching as needed). Skills used for this method (Vital Blessing can replace Succor, and works better as you can also cast it on yourself).
Build bar (template code: OwAT0yHDzIlS0hxTk/jmyDA):



Approach 3: Tricking the Timer
Note: The Jade Scarabs that are needed to do this method does not always spawn or close enough. Several tries may be required to do it this way.

Requirements:

A Monk/Necromancer or Necromancer/Monk with Necrotic Traversal or Consume Corpse, and Rebirth.
Sunspear Rebirth Signet can replace Rebirth in a pinch, but it can't be used again until a boss is killed. Make sure the party member rebirthed with the signet has the Rebirth skill loaded, to get the rest of the party down.
Other party members must have vampiric weapons or other means to kill themselves, such as health sacrificing skills like Order of Pain.
One party member should bring a longbow.
When the party brings the Ghostly Hero on the altar, the timer starts, the drawbridges drop, and the enemies come running in. However, instead of bringing the hero to the altar, he can be commanded to wait outside the fort (by running up to him and talking to him), and head to the south bridge across the fort interior (the party may kill the enemy Ghost Hero if it pleases them, just keep the allied Ghost Hero off the alter so as to not trigger the timer). The drawbridges will remain upright so long as the Ghost Hero does not begin his ritual upon the throne. Therefore, the next part will be dependent wholly upon whether or not any member of your party can aggro any hidden Jade Scarabs waiting across the trenches that lie between you and the bonus objectives. The spawning points of the Scarabs vary from attempt to attempt, meaning you may have to restart if your party seems unable to get any enemy attention. The work will be worth the benefits, however, when you have all the time in the world to kill the Forgotten Generals. Remember to scan the entire wall, south, east and west since scarabs have been known to spawn along the entire wall.

When a Jade Scarab is finally aggroed, lured, and killed from afar, get the Monk/Necromancer in the group to use Necrotic Traversal to jump across to the bonus area via the fresh corpse. Note that you can sometimes lure the first boss with a longbow and exploit their corpse instead or as well. Once this feat has been accomplished, have the rest of the party members equip weapons with vampiric attributes. The point of this is to actually have the rest of the party members die, so do not have them fret or start healing themselves. Once they are dead, the Monk/Necromancer can use Rebirth to transport them across to where he or she is.

Alternate Approach 3 Method

If the party does not have means to suicide:

Leave the Ghostly Hero at point B on the map
Make your way to the south gate and lure in the first General/Jade Scarab with a Longbow or an aggro and kill it from afar
Use Necrotic Traversal to cross the cliff
Run your party back down the north bridge where you left the Ghostly Hero
Turn right and run along the path marked red on the map to where a small cliff is jetting out above the sand
The Monk/Necromancer or Necromancer/Monk can walk along the path marked dark yellow to meet up with the group
The group should have found at least one Jade Scarab and should lure it towards the cliff
Make the group take off their armor and let the Jade Scarab kill off the team
The Monk/Necromancer or Necromancer/Monk can now easily Rebirth everyone in the party up onto the cliff
Continue back south down the yellow path to encounter the last two Generals
Notes:
If you do not have a vampiric weapon, you can also open a trade window with a player with a vampiric weapon equipped. After they die, and are rebirthed across, they can unequip the weapon, place it in the trade window, and trade it to you. Just make sure you give back their weapon.

An Alternative way to get the team killed is for the same person who equipped Rebirth to also bring Unyielding Aura. Before getting to the area where you cross, have the team kill themselves, and then Resurrect them using Unyielding. Once on the other side, just start dropping the Unyielding Aura and Rebirth everyone to the other side.

It is not necessary to kill the Enemy Ghostly Hero to start the bonus; the killing of the Generals will complete the bonus regardless, so there is no need to leave one player inside the fort, unless you want to do the mission as well, in which case that player must go back and bring the ghost to the altar.

Jade Scarabs are melee attackers, so they will flee out of range if repeatedly attacked from the ledge. It is best to lure them in with a single shot, if needed, and then finish them off quickly with spells.

If you're lucky, the boss standing outside the base can be lured in. If you're really lucky, the boss won't be the warrior boss, who will flee once you attack, and instead be a spell caster or ranger, who will attempt to fight back, or just stand still. All bosses leave corpses behind, so Necrotic Traversal will work.

Vampiric weapons are not needed but make the bonus go quicker. You can aggro a couple of scarabs and let them poison the party to death. Once the Monk is over just keep healing the monk and the scarabs will keep poisoning you to death. Once dead, Monk can use rebirth. This takes a good monk because you are putting the party members in harms way with the scarabs. You could use Peace and Harmony to keep your pips up after using rebirth.

The bonus can be achieved using this approach even when you only have henchmen and heroes. Make sure one of your heroes (if not yourself) is equipped with Rebirth and Necrotic Traversal. Once you have a suitable corpse over the wall, activate the traversal from the hero's skill bar. Start the process of killing yourself, and make sure you've deactivated everyone's healing skills. You might want to set a flag for you party further down the hill if you are using a monk henchman. Once you die, the hero will automatically Rebirth you. Pass your vampiric weapon (or whatever) through your inventory to your hero, rinse, and repeat until everyone is over the wall. You'll have to leave your henchmen on the ledge, but you won't need them. You and your heroes should then slowly approach each of the three boss groups, activating and pulling any scarab spawns so as to deal with them separately. If you flag your heroes correctly, you can even pull the bosses away from their escorts. Divide, conquer, and collect your bonus. PLEASE NOTE - there is a strange "bug" when using this approach. If you teleport yourself to the other side and turn the hero/hench flag off after moving away from the drawbridge(more than radar range), it is very possible that your henchmen and/or heroes will "teleport" to the other side by their own and join you in the fight. The mechanics behind this "bug" are currently unknown. For further information please refer to this mission's talk page.

In addition to the Jade Scarabs littering the area, there are several Enchanted Bows stationed at points 2 and 3 on the map. Both are convenient for reducing the death penalty incurred by suiciding.

Alternate Alternate Approach 3 Method

Have all party members become half necromancer so they can all equip necrotic traversal. Have at least one strong party member bring flesh golem.

Jump that party member into the bonus area using necrotic traversal by any of the methods listed above.

Then, if there are no more scarabs near by to use as corpses, that member will go find additional scarabs, kill them, and then use flesh golem (which leaves an exploitable corpse when it dies) to bring the corpses back into range of the remaining party members. Each time the flesh golem decays, its corpse can be used to ferry another party member across.

Repeat this until all party members (or a sufficient number) are across, then complete the bonus.

This method is easily done using only heroes and henchmen since it does not require suiciding and incurring a death penalty.

Approach 4: Early Advantage

Right after you've entered Temple of Ascension and killed all incoming enemies, tell Ghostly Hero to 'Stay Here' and head to the south bridge, as if you're going to use the 'Tricking the Timer' approach. But instead of traversing to the other side, just kill the boss and its friends in '1'. Now sometimes they will be out of reach, so someone with a Longbow should stay there and the others walk away slowly. The enemies should start walking forward and in-reach of the Longbow'er. Using this tactic you can manage to kill the first General. Then kill the Enemy Ghostly Hero and do as 'Approach 1' says. It should save you some minutes and might be enough time, after killing all the Generals, to complete Mission itself.

Approach 5: IW Hero Approach (Requires Nightfall)

This mission & bonus becomes very easy with heroes and Illusionary Weaponry. The advantage with Illusionary Weaponry is that the damage is armor ignoring and it ignores the effect of Blind. Illusionary Weaponry can be easily captured from the boss immediately south of Camp Rankor (part of Drok's run).

Party Setup
Equip yourself and 1 other hero with Illusionary Weaponry.
Equip Norgu with Illusionary Weaponry, Flurry, Power Return, Conjure Phantasm, Imagined Burden. Disable Conjure Phantasm and Imagined Burden to disable auto casting.
Include one hero monk with Protective Spirit and Light of Deliverance.
Include one healer henchman monk
Include one human pure monk or half monk.
Walkthrough
After putting the hero onto the altar, a 10min countdown timer will start. The human monk should stay with the hero at all times.

Kill 4 x 2 groups of Forgotten Arcanists attacking the ghostly hero(earth elementalists)
Head south and kill 1 x 3 group of Enchanted soldiers(rangers & warriors)
Keep moving south and across the bridge and kill 2 scarabs (might not spawn). Cast Conjure Phantasm from Norgu and any other damage spells from you or your other hero. Illusionary Weaponry will get stripped.
Proceed south to kill the first general guarding the entrance to the general's fort. Cast Imagined Burden if it is a monk boss and it runs away from you.
Time check (approx 5:30-6:00)

Head back to your ghostly hero. Defend the hero against 1 x 2 group of Enchanted soldiers. It is important for the human monk to let the ghostly hero tank the forgotten soldiers.
Kill Boss group (5 enemies) to the right of Ghostly Hero.
Time check (approx 3:30)

Go to the fort and kill the remaining 2 Forgotten generals. There is another group of hidden scarabs inside the fort that will appear. Make sure you take the scarabs out before engaging the generals.
Time check (approx 1:00)

One more wave of forgotten soliders will rush hero around 0:30 secs. Again, it is important that the human monk let the Ghostly Hero tank.
Since there is about 1min left over, do not feel rushed if you fall 30-60secs behind. Remember: You must kill the 3 forgotten generals AND their bodyguards to receive the bonus.

Note: After defeating any of the three Generals and all their minions, a group of three random enemies will spawn nearby and head for the east or west entrance to the fort. Usually this consists of two Forgotten Cursebearers and one Enchanted Sword. They will quickly take out the Ghostly Hero, providing yet another incentive to finish the bonus quickly and/or leave at least one party member behind to take care of the Ghostly Hero. (If using Approach 3 or a variant thereof, this is of little importance, since the bridges won't be down yet.)

Approach 6: Hero build for monks (Requires Nightfall)

This is a straightforward, brute force method.

Hero requirements
A Fire Elementalist with Searing Flames
A Minion Master Necromancer with Jagged Bones
Bonder Monk using Life Barrier, Life Bond, Essence Bond, Balthazar's Spirit, and Blessed Signet (the other slots aren't needed).
Fill in your remaining 2 slots with the warrior henchmen.
Walkthrough
Have your monk hero bond the ghostly hero at the start. Life Barrier, Life Bond, Essence Bond, and use Balthazar's Spirit on itself.
If possible, kill the boss to the south as in method 3 to save a little time.
Place your monk hero on the bridge that you used to enter the altar area. Out of aggro range of the altar, but still within radar range so that it doesn't lose the bonds on the ghostly hero.
Have the hero capture the altar. Stick around and kill off the first wave or two of attackers.
Head south and kill the generals as fast as you can. Ignore the wurms.