Lycanthropy

If the player contracts Lycanthropy the player will turn into a Werewolf. There are two ways to contract this disease: being attacked by a werewolf, or participating in a ritual that will require you to drink the blood of a werewolf. When you become a werewolf, you acquire a new power known as Beast Form. This allows you to transform into a werewolf once a day. Once transformed, you remain as a werewolf for 2.5 minutes of real time. You can extend this time by approaching a corpse and feeding on it by activating it as if you were looting it. This restores 50 points of Health, and gives you another 30 seconds of time as a werewolf. Beast form can be extremely useful in situations where your equipment is removed, such as during the quest No One Escapes Cidhna Mine .

Becoming a werewolf is easy, all you must do is join the companions located in Whiterun, you can find the hall near the battle-born manor. Once a few quest's have been completed for them, you should be approached by Skjor or Aela the Huntress. ( if this does not happen, go talk to them and ask for work) You will then meet them in a secret location and be part of the blood ritual. Once you have drank the blood, you will find yourself outside in whiterun as a werewolf. Just run around and dont die. Once this is done, you will be given a quest to wipe out werewolf hunters.



Beast Form Transform into werewolf form Part of Companions Quest: The Silver Hand

Ring of Hircine Transform into werewolf form The Ring of Hircine only works if you are already a werewolf, allowing you to transform into a werewolf at any time, assuming you aren't already in transformed state. (Note: to use, wear the ring, go into powers menu, select Ring of Hircine, and use powers key (default 'Z' on PC). Reward for Daedric Quest: I'll Met by Moonlight

Howl of Rage Fear nearby foes up to Lvl 25, 30s Beast Form only; default Howl. (Totem of Fear)

Scent of Blood Detect Life in a large, 60s Beast Form only; replaces Howl of
Rage; available after Companions Radiant Quest: Totems of Hircine. (Totem of the Hunt)

Howl of the Pack Summon two wolves to fight at your side
Beast Form only; replaces Howl of Rage; available after Companions Radiant Quest: Totems of Hircine. (Totem of Brotherhood)

Vampirism

Players can contract the vampirism disease, Sanguinare Vampiris, through combat with a vampire. The player will be notified when they have contracted the disease and will have 72 hours to cure his or her self. After 72 hours, the infected player will become a vampire, obtaining the abilities of a stage one vampire. The player can cure themselves at an altar of a church or altar in front of a Statue of the Eight (ie. Talos in Whiterun), before becoming a full vampire. Vampirism benefits in past games have varied greatly (including stat increases, new spells or powers, or even new game play mechanics).
Sanguinare Vampiris is easiest to contract in Broken Fang Cave due to the two fairly weak vampires living there. If the player has high enough magicka and enough magicka potions, they can just keep healing themselves with the healing spell, and let the vampires attack them until they contract the disease. Another tip is to turn the game difficulty down in the menu, this way the vampire attacks will cause very little damage allowing you to contract the disease with minimal risk of death.

Vampire Tiers and Skills
Benefits and Disadvantages of Vampirism

Stage One
Abilities:
Champion of the Night- Illusion spells cast by your vampire are 25% more powerful.
Night Stalker's Footsteps - Vampires are 25% harder to detect while sneaking.
Resist Disease - Your vampiric blood gives you 100% resistance to disease.
Resist Frost - Your vampiric blood gives you 25% resistance to frost.
Resist Poison - Your vampiric blood gives you 100% resistance to poison.
Weakness to Fire - Your vampiric blood causes you to be 25% weaker to fire.
Weakness to Sunlight - Health and stamina do not recover while in sunlight and are reduced by 15 points; however, magicka still regenerates normally (only when you are outside during the day).
Powers:
Vampire's Servant - Reanimate a weak dead body to fight for you for 60 seconds (can only be use once a day).
Vampire Sight - Improve night vision for 60 seconds (can be used multiple times a day and be toggled on/off).
Spells:
Vampiric Drain - Absorb 2 points of health per second from target (novice destruction spell, cost of 5 magicka per second).

Stage Two
Changes from Stage 1:
Resist Frost - Your vampiric blood gives you 50% resistance to frost.
Weakness to Fire - Your vampiric blood makes you 50% weaker to fire.
Weakness to Sunlight - Health, magicka and stamina do not recover while in sunlight and are reduced by 30 points (only when you are outside during the day).
Vampire's Servant - Reanimate a more powerful dead body to fight for you for 60 seconds (can only be used once a day).
Vampiric Drain - Absorb 3 points of health per second from target (novice destruction spell, costs 10 magicka per second).
Powers:
Vampire Seduction - Creatures and people up to level 10 are calmed (cease to fight) for 30 seconds.

Stage Threee
Changes from Stage 2:
Resist Frost - Your vampiric blood gives you 75% resistance to frost.
Weakness to Fire - Your vampiric blood makes you 75% weaker to fire
Weakness to Sunlight - Health, magicka and stamina do not recover while in sunlight and are reduce by 45 points. (only when your outside during the day)
Vampire's Servant - Reanimate a powerful dead body to fight for you for 60 seconds. (can only be use once a day)
Vampiric Drain - Absorb 4 points of health per second from target. (novice destruction spell, costs 12 magicka per sec)

Stage Four
Changes from Stage 3:
Resist Frost - Your vampiric blood gives you 100% resistance to frost.
Weakness to Fire - Your vampiric blood makes you 100% weaker to fire.
Weakness to Sunlight - Health, magicka and stamina do not recover while in sunlight and are reduced by 60 points (only when you are outside during the day).
Vampire's Servant - Reanimate a very powerful dead body to fight for you for 60 seconds (can only be used once per day).
Vampiric Drain - Absorb 5 points of health per second from target (novice destruction spell, costs 15 magicka per second).
People will be hostile towards you and might attack you on sight.
Powers:
Embrace of Shadows - The vampire becomes invisible, with improved night-vision for 180 seconds (can only be used once per day).

Vampires grow in power by NOT feeding. If you want to become a Vampire with abilitiies higher than tier one, do NOT feed on anybody. Feeding will always bring you back to tier 1 of vampirism, regardless of what tier you were before feeding.
In the early stage of the vampirism, NPC's will act normally with you.
On stage 3, they will not interact with you unless you speak to them (you are feared, but not hated).
On stage 4, you are considered hostile with everyone, so be careful! (tip: use your invisibility ability to sneak in a house to feed).
You can feed on sleeping NPCs in the same way you'd pickpocket from them. This takes you all the way back to stage 1 of the disease.
If you are having trouble feeding at level four vampirism, you can travel to an abandoned camp or shack, and ask your companions to sleep by asking them to do something for you, and then hold the action button on the bed, you will have a very short window of oppurtunity to feed on them however, but this is a safe and convenient way to deal with hunger.


So there we have it, two ways to become a machine of death. I hope you found this informative and can you please post your experiences and stories, or report anything in the topic that no longer works (maybe due to a recent patch). Thank the topic! Note: The description on werewolves and the powers may be vaguer than vampires as there is still alot to be found about them. The topic will be updated with the latest info as soon as said info is available.

Source - Various sites, mostly wiki's and fan forums.



Simple Gameplay




Vampirism Gameplay/feeding Farm



How to cure vampirism