Knight Artorias

Knight Artorias also known as Artorias the Abysswalker is a boss in Dark Souls. He is exclusive to the Artorias of the Abyss DLC.

Location
In the colosseum area of Oolacile Township, at the end of the Royal Wood.

Description
By the time the Chosen Undead encounters him, he is shown to have already been corrupted by the Abyss; the reason for his armor's putrefied appearance and the aura of darkness that it oozes. His crippled arm is likely the result of Artorias halting the spread from devouring his wolf companion by means of a now missing shield. He possesses a greatsword that has also been consumed, yet is still far from ineffective. Having lost his sanity, the knight moves about in an untamed manner as he howls beneath the blue shroud of his helm.

Lore
Sir Artorias the Abysswalker was one of the Four Knights of Lord Gwyn. He only makes an appearance in the past as he is deceased by the time the Chosen Undead escapes the Undead Asylum.

Knight Artorias wore distinctive armor, as well as the Wolf Ring and brandished his Greatsword and Greatshield. He is also known to have been a friend to Alvina of the Forest Hunter covenant and Sif, the Great Grey Wolf, who guards his grave and keeps the Covenant of Artorias ring in his possession.

Artorias hunted the Darkwraiths and was able to traverse the Abyss with the power of his ring, which he gained after making a covenant with the beasts there, preventing him from being swallowed by the void and cursing his sword. In recognition of his actions, he was awarded one of Anor Londo's treasures, a Silver Pendant that allowed him to repel Dark sorceries.

When Oolacile became threatened by the Abyss created by Manus, Artorias and his wolf companion, Sif, arrived there to save Oolacile and rescue the abducted Princess Dusk. However, the two were overrun and Artorias sacrificed himself to protect Sif using his Cleansing Greatshield, erecting a barrier around the young wolf. Swallowed by the Dark, he became corrupted along with his sword. He was then finished off by the Chosen Undead after the encounter in the colosseum of Oolacile.

Melee Strategy
While this boss is really difficult to predict, he does have a few tells for his attacks and a quick roll is very important. Place yourself away from him by about twice his reach at all times (even for melee).

Aerial Attacks
(See below for attack name references)

When he uses his Somersault slam attack you will want to roll to the right as the camera tilts upward while locked onto him. You want to do this three times and then get in 1 or 2 attacks (based on your weapon) after the third attack lands. Avoid attacking after his Steadfast Leap. Instead use that opportunity to heal or get some distance from him.

Standing Attacks
When he uses his Overhand Smash, roll to the right. While he leaves himself open for a frames, he will usually follow up with his Spinning Slash attack. Therefore it is best to get some distance from him instead as the Spinning Slash attack is difficult to get away from when it begins.

Charging Attacks
With his Charging Slash move you will always want to roll backwards from where he intends to land the attack. After successfully dodging this attack, you will be able to get 1 or 2 hits on him.

His Heavy Thrust attack will need to be side dodged. Depending on which way he turns during the charge, you will need to dodge the opposite way. After you dodge he has a long recovery time and you should be able to get 2 or 3 hits in.

Other Attacks
When you are behind Artorias he may use his Abyss Sludge attack. This move does little damage but can stun you. If timed right, you can roll forward through the attack and get a hit on him then immediately retreat.

After Artorias has lost 1/3 of his health he will start to use his Wrath of the Abyss power up. If left alone, he will do much more damage after he completes the power up for a limited time, potentially one shotting you. If you can get close fast enough, you can stun him out of his power up before it's completed by hitting him repeatedly. If you don't do enough damage fast enough then he will hit you with an AOE blast attack that will knock you on your back. Your best bet is to use a heavy, high damage, weapon and stop him from gaining his attack buff.

Steadfast Leap
Artorias crouches, then leaps high into the air towards the player, causing damage in a small area-of-effect around him. Rolling or moving towards him instead of away can increase one's chance of successfully dodging before he lands.

Somersault Slam
Artorias somersaults into the air after which he slams his sword down vertically. He can repeat this up to three times. Roll to the side to avoid it. The player can be stun-locked in this combo.

Overhand Smash
Slams his sword overhead and towards the ground; high staggering power that leaves his guard open for a short time after it lands.

Charging Slash
Artorias bursts toward the player and swings his sword 360 degrees. He presents an opportunity to be attacked after it lands.

Heavy Thrust
Pauses before performing a heavy, medium range thrust towards the player. If it connects, it can hit twice, dealing heavy damage and knocking the player to the ground.

Spinning Slash
Artorias quickly spins, completing a full revolution. It has the potential to connect twice.

Abyss Sludge
Artorias throws a staggering sludge in a wide arc, a few feet in front of him. Usually performed if positioned behind him.

Wrath of the Abyss
Activates in intervals after approximately 20% of his total health is reduced. After attempting to roll away, he will slowly build up magic energy, presenting ample time for retaliation, potentially staggering him, or to apply augmentations to one's weapon or self. If allowed to, he will release an explosion that does Magic Damage in a mid-ranged area of effect all around him. Artorias' attack speed, area-of-effect and damage are enhanced for a limited time afterwards.

In addition to the health thresholds, this attack has a time interval between uses, in that if Artorias is left undamaged for a period of time, he will re-activate Wrath of the Abyss.

Trivia

 * Artorias, like many characters, had unused content that was hidden between the game files. Here is the dialogue that was kept out of the final version. Artorias was supposed to have the same voice actor of Griggs of Vinheim.
 * It's implied in Artorias' cut dialogue that he was not human.
 * It is speculated that Artorias had a romantic relationship with Lord's Blade Ciaran before being corrupted by the Abyss.
 * Sif survived the spread of the Abyss when Artorias used his greatshield to construct a magical safeguard around his partner, leaving Artorias' arm and the shield's physical material vulnerable to the Dark.
 * Artorias' design may have been based off of the character Guts (also known as Gatts or Gattsu), the main protagonist of the manga series Berserk. Many similarities can be found between the two. Both Artorias and Guts use a greatsword and a handicapped arm (Guts has a prosthetic left arm), and Artorias's sommersault attack is very similar, if not the same, to Guts's Spinning Jump Attack when he wore the Berserker Armor. In addition to this, Artorias has a wolf companion, Sif, whilst Guts has an inner canine-like personality, which is named Hellhound.