Four Kings

The Four Kings are bosses in Dark Souls.

Location
The Four Kings are found in the Abyss, accessed through New Londo Ruins. The player must first acquire the Key to the Seal from Ingward to drain the water from the ruins, as well as the Covenant of Artorias, a ring obtained from Great Grey Wolf Sif, to safely enter their battle arena.

Lore
The Four Kings were once great leaders of New Londo, and, in recognition of their foresight, Gwyn granted them their ranks and apportioned fragments of a Lord Soul discovered from the First Flame. When the Four Kings were seduced by evil, their knights became Darkwraiths, users of the art of Lifedrain. In an effort to contain the threat they posed, New Londo was flooded, trapping the Four Kings and the Darkwraiths in the Abyss, and sacrificing the city of New Londo and the countless lives therein.

Summoning
Summon signs are most commonly found at the beginning of the New Londo Ruins, before crossing the bridges. Some can also be found right before the boss door.

Witch Beatrice's summon sign can be found hidden around a corner just before crossing the short bridge to the Fog Door. It may prove more than useful if you are a light build.

Strategy

 * Unequipping the Covenant of Artorias will result in the player dying immediately; you cannot unequip this ring while fighting the Four Kings. After the battle has been completed, the ring is no longer necessary and may be unequipped without dying.
 * Upon entry, the player will have time to cast any sort of buffs, during which a single king will appear; the second will join approximately one minute later; the last two appearing in the minute following. It is vital to eliminate each King quickly to avoid being surrounded.
 * There is no obligation to kill any specific amount of kings, so it is possible to spread out the damage to several of them. This can be done by dealing massive postmortem damage to a single King, as they can still be hurt during their death animation.
 * Power Within adds decent amounts of damage to attacks and can help destroy individual Kings quickly before the next one appears.
 * The use of Great Magic Barrier, Magic Barrier, or any equipment with high magic resistance can help, as all of their attacks deal at least partial magic damage.
 * The damage dealt by the Kings in NG+ is far greater than in NG, so it may prove difficult to absorb their attacks with heavy armor.
 * Staying close to a King will force the lower portion of the blade to hit, minimizing damage. This is true even on NG+, as getting hit by the upper section of their blade will deal heavy damage. This will also prevent it from using some magic attacks (namely, the homing shot) and the unengaged Kings tend to use melee at most distances.
 * Using a ranged attack and staying at around 1-1.5 roll distance away in front of the king (just within the reach of his sword) makes him rely mostly on the vertical slashes and the occasional Homing Abyss Arrow or Life Drain (Wrath of the Kings might even be prevented entirely, but this is unconfirmed). The Life Drain is also easier avoided since it looks less like Wrath of the Kings at this distance then it does close up, and the player already has a head start on getting out of reach.
 * Their homing attacks can be deflected by using Force or Wrath of the Gods, although it is safer to avoid the attacks entirely. Due to the speed at which the King approaches, the player will become vulnerable to other attacks during the casting animation. Deflecting the large homing shot will likely be fatal, since the duration of the attack lasts a fair while and doesn't collide with anything other than the player.
 * Initially, it can be hard to determine how close a king is; they can appear close, when they are in fact out of reach. It's a good idea to run into a king before attacking, not only to be sure your attacks will land, but also because being close to a king can cause his attacks to miss.

Double Horizontal Slash
Two wide sweeping slashes with the King's sword. May occasionally stop after one attack. These have excellent tracking and are quite damaging to health should a critical hit land. Stamina is largely drained when blocking both consecutively. They can be rolled under, and can be sidestepped away from without taking damage.

Vertical Slash
Powerful vertical slash. Does not track, however, blocking is not recommended, as massive damage to the stamina bar is guaranteed.

Forward Thrust
Single powerful straight thrust with the Four King's Sword. It has the longest reach of all melee attacks and deals massive damage when absorbed head on. This attack is only triggered when the player is at a distance and cannot be strafed; although it has poor tracking and can be dodged.

Double Slash
Two diagonal slashes with the Sword; may take a fair amount of stamina to block. May stop after one attack.

Wrath of the Kings
Extremely powerful, large area-of-effect attack in which the King will spin around, covering himself with his left "wing" and emanate a purple aura. Blocking is most successful when using a high stability shield with good magic reduction. Otherwise, players should release their lock and run away when the King begins his attack.

Homing Arrow Mass
The King will fire off six energy shots that home in on the player. These are much quicker than Homing Abyss Arrow, but they also have much weaker homing capabilities, allowing the player to easily roll or move away when they approach. Getting hit by multiple shots will deal immense damage.

Homing Abyss Arrow
The King will fire off a slow moving, large, purple projectile that has high tracking capability and powerful magic damage. It cannot be evaded and may only be blocked by a high stability shield with high magic resistance; which will likely drain the entire stamina bar, but may also reduce the damage. The only way to avoid this attack is to outrun it until the projectile disappears. A new king might spawn within that time period.

Life Drain
This is a Humanity stealing grab attack, and, like all grab attacks, it is unblockable. Its animation is similar to Wrath of the Kings: the King will spin around and pause, holding its wing/arm in preparation while emanating a colorless aura. If the player is slow to react, his forward grabbing dash will be inescapable. Counter-intuitively, it can be avoided by moving closer to the attacking king before they begin their lunge. In extreme proximity the attack will simply go over the player's head. This attack can be fatal if the player is not using armor with high magic defense. Unlike other grab attacks, the King can still be damaged by aiding phantoms as a player is drained; however, this will only deal damage to the Four Kings' collective health bar rather than the individual King.

Trivia

 * The sword used by the Four Kings was intended to be in the game, however, it was removed from the final version of the game.
 * The Four Kings are the only holders of a Lord Soul or Bequeathed Lord Soul Shard that are not shown in the opening cinematic.