Nature of the Beast

Background
The Dalish Elves are being destroyed by a virulent disease which is turning them all into werewolves. The clan keeper, Zathrian, asks for your assistance in ridding them of the curse. He requests that you find Witherfang and remove his heart to end the curse destroying his people. You need to investigate the Brecilian Forest to see if you can find more information to end the curse.

Walkthrough
Zathrian sends your party into the forest to find Witherfang and remove his heart to end the curse destroying his people. Before you leave the Dalish camp, it is possible to pick up four side quests -- see the Sidequests section below for more details.

The Brecilian Forest has two sections (West Brecilian and East Brecilian), each of which should be explored completely. You will also come across tombstones which can be activated as part of The Mage's Treasure quest -- the only way to get a full set of Juggernaut Armor in the game.

As you travel through the first section of the forest (West Brecilian), you will fight a lot of werewolves. Eventually you will reach a waterfall with three paths and three werewolves standing within it. This is the first encounter with Swiftrunner, a werewolf who appears to be in charge. He speaks to you; with enough persuasiveness, this encounter does not need to end in battle. After either a peaceful or a violent resolution to the encounter, The Warden can continue into the woods.

In the following area lies a fallen hunter, and The Warden may choose to either let the hunter return to camp or to kill him (Wounded in the Forest quest).

Before leaving the first section of the forest and crossing into the East Brecilian Forest, look for the large tree fallen across the water; the tree contains the Ironbark necessary for the Rare Ironbark quest.

The second area of the forest once again has Werewolves and Wild Sylvan as random encounters. On one of the paths, the Lost to the Curse quest can be continued by speaking to the werewolf lying there. Note: Lost to the Curse can be triggered before you leave the Brecilian Forest by speaking to Danyla's husband.

A section of the forest is protected by an impassable barrier. In order to continue the quest, a way to remove the barrier must be found. At this point, you will be required to explore both sections of the Forest thoroughly in order to find the Grand Oak (in the West Brecilian Forest) and the Mad Hermit (in the East Brecilian Forest).

Note: Near the Grand Oak is a campsite. Make sure to save before going near it -- it leads to a possibly fatal encounter. Examining any of the campsite items (tent, fire, sleeping bags) will cause several dialogue options to show up; failing to resist the temptation leads to the party falling asleep and possibly being defeated without a fight. (This can vary; see the Talk page for more details.) In order to ensure survival, attempt to leave after without examining any of the items, after a short dialogue option a Shade will appear. After the Shade is defeated, the campsite will change, and several chests and corpses to be looted will appear. In the chest under the tree are the Dalish Gloves gift for Zevran and the Dusk Ring necessary to trade with the Mad Hermit.

The answers you give to the various dialogue options seem to affect which of the current party members will be available to help in the battle. The surest way to tackle the shade here is not examine any of the items at the campsite. Simply walk into the campsite, go through the dialogue that the set up is odd or dangerous (depending on your companions) and then try and leave. You will automatically be brought back to the campsite and will have a final dialogue option before the shade attacks your party. If your character throws their hands up in the air, you will be battling with your entire group. If however there is a momentary black screen, you only have one party member awake who has to attempt to defeat the Shade on their own.

Getting through the forest barrier
There are two options available. You will encounter the Grand Oak, who will give you a branch to help you cross the barrier if you retrieve his acorn. His acorn is being held by the Mad Hermit, who wants to keep the acorn.

When siding with the Grand Oak (that is, retrieving its acorn), you may choose to either kill the Hermit or to trade The Tale of Iloren (book from Cammen's Lament quest), a Dusk Ring, or a Scarf (from Lost to the Curse quest) for it.

To side with the Hermit, simply attack the Grand Oak.

Warning!: Some Xbox 360 players have reported experiencing a glitch where the werewolf pelts may disappear from the inventory, resulting in not being able to gain access to the ruins through the Hermit if the player has already killed the Grand Oak.

''Note: Stealing from the Hermit's tree stump will result in him turning hostile, forcing you to kill him. What you steal from the tree stump is actually the acorn so don't panic if you don't find the acorn on the Hermit's body as you have already stolen it from his 'home'.''

Note: Trading the Hermit for the Acorn will allow the Warden to loot the tree stump, receiving the Golden Ring instead of the Acorn.

Upon passing through the barrier, The Warden will once again encounter Swiftrunner. It is impossible to avoid the battle, despite the persuasion options. After the battle is completed, Witherfang appears and the rest of the werewolves scatter. It is now possible to access the Temple Ruins. Note that the Ruins will contain a great deal of loot requiring up to 80 empty inventory slots if the player intends to gather it all during a single visit.

Temple Ruins
There is little to do here other than to press on. The werewolves have locked the main door to their lair, leaving The Warden no choice but to take the long way. One of the rooms in the temple contains an altar room, which although listed as a quest unto itself (The Elven Ritual) it is also a necessary part of The Mage's Treasure quest. A Black Vial is found in one of the other rooms of the ruins. Finally, there is a broken altar and Phylactery which can be used to unlock the Arcane Warrior specialization. The entrance to the werewolves' lair is a pool of water, which the Party must to dive into.

Werewolves' Lair
Upon entering the lair, The Warden is met by Shadow Werewolves. They are generally tougher than standard werewolves, will first be encountered in a room littered with traps. Having a rogue disable the traps makes the battle easier. When the main lair is finally reached, there is an opportunity to parlay with the Lady of the Forest. Accepting this opportunity allows The Warden to make a further decision as to the outcome of the quest.

The Warden's Choices
If the warden parley's with the Lady of the Forest she will make the Warden aware that the curse began with Zathrian, when he cursed human settlers who murdered his son and raped his daughter. The current werewolves are not all the same werewolves who were originally cursed. Many are but poor souls who wandered into the forest and were caught up in it. The Lady of the Forest asks that the Warden bring Zathrian to the chamber so they may talk.

Kill The Elves
With a high enough persuasion, the Lady of the Forest can be convinced that the best course of action is to kill all the elves. Killing the elves and siding with the werewolves results in negative approval from many of the companions including those who may not yet have been recruited. Any character with a high moral ground will not approve of this choice. Morrigan, however, thinks it's a wonderful idea. With the elves dead the weres will agree to fight for the Warden and march with them against the darkspawn. All other resolutions result in the elves fighting for the Warden.

Note: While killing the elves gains you the Werewolves as an army in the final battle, This will leave the you with mages as your only ranged damage dealing army option in the final battle.

Kill The Werewolves
As expected, party members like Leilana will react badly to this choice.

If the Warden agrees to bring Zathrian before The Lady of the Forest he will be encountered as the Warden exits the ruins. Once Zathrian is brought to The Lady of the Forest the Warden can choose to engage the weres with Zathrians help, who will tank Witherfang for much of the fight but will frequently freeze the party with Cone of Cold without careful positioning.

After the battle is over, speak to Zathrian again. He will give you an item, and if you go back to the west Brecilian forest, you will meet a group of hunters who will reward you as well.

The Warden has the option to doublecross Zathrian battling him with four sylvian, two yellow shades, and the remaining werewolves. Zathrian does not regen between fights and will have very little HP remaining if he was significantly damaged or knocked out in the fight with Witherfang.

This option gives you substantially more xp and loot than lifting the curse. Lifting the curse actually gives you no loot at all, aside from swiftrunner's shield.

Note: On the console version It is possible to gain the Achievment 'Slayer' yet still side with the Elves, this requires however for you to save your game just before you enter the lair, and after you gain the achievment by completeing the dialogs in aid of the werewolves, you load your game again and then choose to slay the wolves, you will keep the achievement yet choose to aid the Elves 

Convince Both Parties to Lift the Curse
If the Warden elects to talk it out with Zathrain and The Lady of the Forest Zathrian can be convinced to sacrifice himself to lift the curse together with The Lady of the Forest. Zathrian will not accept without a fight, however, and will engage the Warden, the weres, and Witherfang with the party described above. After Zathrian is defeated he will agree to help end the curse, The Lady of the Forest and Zathrian will both die, and the weres will return to their original, human forms. At this point the Warden may speak with Swiftrunner, now a human, who will thank the Warden for their help. If the Warden asks for a reward Swiftrunner will give the warden his shield. The Warden may choose to double cross the now human weres and slaughter them. They offer little resistance in their human forms.

The fight with Zathrian consists of two Greater Shades, several Great Sylvans, and of course Zathrian himself, who is a powerful caster. The werewolves themselves cannot initially join in the fight because they are each encaged within a forcefield of sorts. To make the fight exponentially easier, have a party member cast a dispelling spell (such as Alistair's Cleanse Area) close to the werewolves to release them. Most of the werewolves should automatically engage Zathrian, interrupting many of his large AoE spells. Note that the fight ends as soon as Zathrian "dies," so all the player must do is stay alive long enough for Witherfang and the rest of the werewolves to do their part.

Other party approval notes
Shale will disagree with the Warden if the Warden chooses to parlay with the Werewolves. This however can be immediately made up in positive approval after speaking with the Lady of the Forest to learn that Zathrian has misled the Warden and companions. Oghren will disagree if The Warden does not outright kill Zathrian themselves and he is allowed to jointly end the curse with The Lady of the Forest. There is no point after making this decision that it is possible to 'make up' the loss of approval points with Oghren. Alistair will approve if the Warden chooses to force Zathrian to end the curse.

Result
Once the curse has been lifted, not only are the ailing Dalish cured (if you did not kill them) but the werewolves again become human and immediately leave the ruin. If you sided with the elves, Lanaya (Zathrian's second) will agree to send troops to assist you in fighting the blight.

If siding with the elves, once the werewolves have reverted back into humans, you can demand a reward from them. Swiftrunner will give you a shield, Swiftrunner's Shield which is quite a nice reward for a guy who's been a beast of sorts for years.

You are now free to explore the Forest to complete the Mage's Treasure Quest. The Mad Hermit's camp is now inhabited by bandits and it is likely that the area beyond the forest barrier is now inhabited by darkspawn. Expect most if not all of these darkspawn to be of the 'Alpha' variety, making this a tough battle if you're unprepared.

If you decided to attack the Elves and side with the Werewolves, you will have Werewolves march to war with you at endgame rather than Elves.

''Result Balance: Note that if you side with the Werewolves, you have lost one of your main ranged weapon allies for the Final Onslaught. Only Mages, Golems (If you side with Branka - though note this is through special attack only), and Elves offer ranged weapon assistance in the final battle.''

Sidequests
There are four sidequests accessible in the Dalish Camp once Nature of the Beast has been started. The ones marked with * resolve themselves without player action if they are not completed before Nature of the Beast has been finished. Note however that they will all end immediately if you side with the werewolves and kill the Dalish.
 * Cammen's Lament * (This quest will end immediately on your return to the Dalish camp if you only return to Cammen after ending the curse.)
 * Elora's Halla (This quest remains available well after the completion of Nature of the Beast.)
 * Lost to the Curse (If you speak to Danyla's husband prior to entering the Brecilian Forest, this quest remains active until you return to the camp to inform Danyla's husband of her fate.)
 * Rare Ironbark * (If you begin this quest before you enter the Brecilian Forest, it will remain open for you until you return after completion of the main quest. You must start this quest prior to completion of the main quest though.)

Codex Objects

 * If this is the first place you go for allies, it will also be the first place you encounter 'Black Vials.' They will each spawn a Revenant.
 * The Werewolves Lair is also where you will find Ancient Elven Armor. If you have already picked up the boots from Lothering or traded the Mad Hermit for the helm, you'll notice you do not get a codex entry. You will get this entry once you have picked up the body armor from the lair.