Lycanthropy

Overview:

Werewolves exist in Skyrim. The disease is known as lycanthropy, (or Sanies Lupus in TES III: Bloodmoon). Any player can choose to become a werewolf by following The Companions Quests.

Werewolf related items

Totem of The Hunt: Detect Life ability.

Totem of Brotherhood: Summon 2 Wolf Spirits.

Totem of Fear: Howling will Fear enemies.

Benefits

The benefits of lycanthropy are few, but rewarding:

Increased health in human form.

Immunity to all forms of disease (including Saguinare Vampiris).

Beast Mode In a transformed state, the werewolf's innate powers enhance your speed and physical strength.

The physical damage you inflict increases by level

Increased Stamina Regeneration Wolves will fight with you while in Beast Mode Howl, see similar spell:Fear Feed on victims to increase time in Beast Mode and regenerate Health. While transformed you can run at full speed when encumbered.

You have to feed on humans. In doing so, this adds another 30 seconds on to your time limit for being a werewolf.

Werewolves use their claws to tear enemies asunder and can use a howl ability, during which affected enemies cower or run from battle. Using this power is almost mandatory in combat as werewolves are just as weak against normal attacks as in their human form and you can easily die in seconds if faced by a group of enemies.

Injuries can be tended to by feeding on the ravaged corpses of human victims. The effect lasts for some time, after which you revert to human form, but a satiated bloodlust can potentially prolong the transformation.

Disadvantages:

The player's current follower might abandon him/her for fear of being ripped to pieces. The werewolf blood in you also prevents you from receiving the Rested buff from sleeping and Silver weapons will do more damage towards you.

Werewolves are also weak against the Undead as the Howl power does not equate to the Turn Undead effect, leaving you wide open to their attacks. Thus you should never shift in Graal or Ghost catacombs, or when fighting Liches.

More Drawbacks:

Cannot get the "Well Rested" bonus anymore.

Cannot regenerate naturally whilst in werewolf form. People tend not to like werewolves.

Silver weapons do more damage.

You cannot become a Vampire and a Werewolf. Lycanthropy can be cured. After finishing The Companions' questline, you'll get a quest that offers a cure. However, take caution: Once you cure it, you cannot become a werewolf again.