Blood Washes Blood

Overview

 * Light the sacred altar. Lead the bear spirit into Bjora Marches to cleanse Jora's homestead. (disappears from Quest Log after speaking to the bear spirit)
 * Accompany Bear on the mountain pilgrimage to the Shrine of the Bear Spirit.
 * Defeat the Charr forces surrounding the Shrine of the Bear Spirit.
 * Receive the Ursan Blessing should be Ursan Aura [sic] from the Shrine of the Bear Spirit.
 * Use the bear spirit skill, Ursan Force, to break down the Charr barricades.
 * Kill the Charr in Jora's homestead. 5...0 groups remaining.

Obtained from
 * Automatically added after completing Flames of the Bear Spirit
 * After first completion, can be obtained from:
 * Bear Spirit in Jaga Moraine (after capturing the sacred altar)
 * Scrying Pool in Hall of Monuments (select "I seek guidance" option)

Requirements
 * Flames of the Bear Spirit

Follow up
 * A Hunter's Pride

Walkthrough
Head to the sacred altar in Jaga Moraine to summon the Bear Spirit. To claim the altar, party members must stand on/next to the edifice, during which time you will be attacked by Arctic Nightmares. The mission progress bar will change from red (enemy held) to blue (lighting the flame). Speak to Bear to initiate the quest, then walk through the portal to Bjora Marches.

Fight your way through the Charr, mandragor, and elementals on your way to the Shrine of the Bear Spirit. The Shrine is guarded by three groups of Charr, each with a boss. The groups follow patrol patterns that make them easy to pull apart from each other. After defeating all three groups, click on the shrine to obtain the temporary skill Ursan Aura, which is required (by at least one player) to reach the charr (see below). The aura is quite powerful, so each player should consider swapping it into their own skillbar. (Note: contrary to the skill description, Totem of Man does not drain your energy; you can switch between the ursan skills and your normal skillbar as needed, suffering only a 30 second cooldown.)

Head for Jora's homestead, invoking Ursan Aura to allow you to use Ursan Force to destroy the barricades blocking the path to the Charr. Destroy all five groups of Charr to complete the quest. After a cutscene, the party will be returned to Gunnar's Hold.

Repeating the Quest
Subsequent runthroughs of the quest can be completed more quickly, as you only need to summon the Bear Spirit, power through the southernmost barricades, and destroy one group of charr. With careful observation of the various patrols along the way, you can avoid most the of the non-Charr foes enroute.
 * Ensure at least one player is equipped with Ursan Blessing (acquired by completing, A Hunter's Pride).
 * Go to the bear altar in Jaga Moraine and speak with the Bear Spirit (nightmares will not attempt to claim the altar during repeats).
 * Return to Bjora Marches.
 * Go directly to the southernmost barricade, invoking the blessing to enable Ursan Force to tear it down. (During repeats, you do not need to detour to the Shrine of the Bear Spirit.)
 * Destroy the southeastern group of Charr (which typically requires going through two more barricades).

Hard mode
There are vastly more Vaettirs guarding the sacred altar in the area in hard mode, and they are much stronger. Vaettirs have extremely high armor and significant self-healing, so it can take a while to wear them down, and their heavy health degeneration can put a considerable strain on your healers. One group of four is manageable, but two at a time is not.

Most of the vaettirs can be avoided by starting from Longeye's Ledge and running through Bjora Marches to get to Jaga Moraine. It isn't necessary to fight anything in Bjora Marches, as the mobs move slowly and are rather spread out. Once in Jaga Moraine, approach the sacred altar from the east side and try to capture from the edge of its range. If you're lucky, you can sneak in, capture the altar, make the bear spirit appear, talk to the bear spirit, and then go back to Bjora Marches to start the mission proper.

If you're not so lucky, you'll aggro vaettirs in the process. There are several linked groups of four that can wander near enough to the sacred altar to aggro on you there, each of which probably won't, but it's likely that at least one will. If you aggro any vaettirs, immediately run away to the east and pull the group you aggroed over there where there is more room to fight. If you stay near the altar and fight, party members scrambling around will likely aggro additional groups and cause a wipe. If multiple groups follow you, keep on running all the way into Bjora Marches and then come back to reset the instance and try again.

Once back in Bjora Marches for the mission itself, hard mode greatly increases the level of most mobs. There are a number of groups of three Charr or five mandragors that patrol long distances with overlapping routes. It helps immensely to pull only one group at a time, though two groups of Charr at a time is still manageable. Charr Flameshielders deal considerable area damage with Fire Storm and Meteor Shower, so it can help to spread out. You may need to wait a while for a convenient time to pull a single group, or pull a group far out of its route to get it out of the other patrol routes.

If you follow the route on the map, you'll only have to fight one mandragor group, but it's quite a dangerous group. The Dreamroot Mandragor uses Fevered Dreams, and the other mandragors spread conditions quite a bit, too, which can easily get four or five conditions on your entire party at once, including Dazed, so that the interrupts prevent most healing. You'll end up with a lot of conditions almost no matter what you do, as removed conditions will very quickly be reapplied. Flagging your party apart will at least mean that some party members are relatively safe. Kill the dreamroot mandragor first, as its fevered dreams is what makes the group so dangerous.

When fighting the five groups of Charr at the end, be aware that Charr Dominators have Resurrection Chant. They must be killed quickly, or else they will continually resurrect anything else that you kill. Most of the groups have two Charr dominators, but no healers. The group with the boss Elmohr Snowmender has only one Charr dominator, but it also has a monk boss that is a very powerful healer, making it the hardest group. It helps to kill the dominator first, then the flameshielder, and then the boss.

NPCs

 * Norn
 * 20 Egil Fireteller
 * Spirit
 * 20 Bear Spirit

Monsters

 * Charr
 * 20 Charr Axemaster
 * 20 Charr Blademaster
 * 20 Charr Bladestorm
 * 20 Charr Seeker
 * 20 Charr Prophet
 * 20 Charr Mender
 * 20 Charr Hexreaper
 * 20 Charr Dominator
 * 20 Charr Wardkeeper
 * 20 Charr Flameshielder
 * 20 Charr Avenger
 * Elementals
 * 24 Frozen Elemental
 * 28 Avalanche
 * Mandragors
 * 20 Mandragor Scavenger
 * 20 Dreamroot Mandragor

Bosses

 * Charr
 * 24 Tenagg Flametroller (Eviscerate)
 * 24 Docu Kindleshot (Barrage)
 * 24 Elmohr Snowmender (Healing Light)
 * 24 Kakei Stormcaller (Mind Blast)

Dialogues
Briefing from the Scrying Pool.