Gwyn is one of the divine Lords that defeated the Everlasting Dragons long ago. His Lord Soul grants him the power of the sun and lightning, making him the Lord of Sunlight. His children are Gwynevere, Gwyndolin, and his firstborn, whose name is unknown, due to the loss of his deity status.
Thousands of years before the events of the game, the First Flame began to dim. Gwyn asked The Witch of Izalith to recreate the First Flame, but the Witch failed and the flame engulfed and corrupted her and her children, creating the Bed of Chaos and the art of Pyromancy. After this incident, Gwyn departed from Anor Londo to rekindle the First Flame, bringing half of his knights with him, while the rest stayed behind to guard Anor Londo. Before he departed, he bequeathed his Lord Soul to the Four Kings of New Londo and Seath the Scaleless. After linking the Fire, the First Flame burned his knights and made him its fuel. Thus, he is known as Lord of Cinder.
He is the final boss in the game.
Solaire of Astora
You must have saved Solaire by killing the red Chaos Bug in Lost Izalith shortcut (the one that needs +2 Chaos Servant covenant to unlock) to be able to summon him here. His Soul Sign is after the third Black Knight (straightsword-wielder). Look left before you walk down the staircase.
- Jumps towards the player when the player is too far away, performing a large overhead slash
- Lunges and stabs when the player is a little out of range of his attacks
- Slashes in quick succession
- Wields his sword in both hands, performing a slower, succession of blows. This attack is not always stronger. At times the faster single handed attack does twice the damage.
- Grabs the player, dealing fire damage and knocking the player back
- Kicks the player when close, usually followed by a grab
- If you keep Gwyn on the higher portion of one of the slopes, many of his attacks will go over your head, making this fight much easier.
- Provoking Gwyn's grab attack and stepping back provides you with a chance to heal.
- Kill the two Black Knights on the stairs before the white light door. They can use their overhead swings to hit you through the gate right after you've gone through.
- Using equipment and pyromancies that reduces fire and physical damage helps control HP loss. Flame Stoneplate Ring, Ring of Steel Protection, and Flash Sweat for instance.
- Stamina regen items help to deal with stamina shortage - Grass Crest Shield, Green Blossom, Cloranthy Ring and the Mask of the Child for instance.
- Weapons that have Occult property do bonus damage against Gwyn. Upgrade weapons via the Occult path or use Priscilla's Dagger or Velka's Rapier to exploit this weakness.
Two-handed heavy melee
Equip your best armor. Rush at Gwyn with a powerful two-handed weapon. He has low defense and can be staggered fairly easily, which provides opportunities to heal. Try not to have your health fall below 50%. In a New Game, this strategy works even better if you cast Flash Sweat as soon as you traverse the white light. With decent Endurance and Vitality, you should only need to cast Flash Sweat once.
Tank Melee with Iron Flesh or Flash Sweat
Equip heavy armor with good physical and fire defense. Using either Iron Flesh or Flash Sweat, two-hand a weapon of your choice and spam him with R1. He staggers easily and his attacks do less damage because of your high defense. If Iron Flesh expires before he is dead, pop a flask and equip a shield. Try to provoke a grab from him and step backwards to recast it.
The Iron Flesh strategy works best for high Vitality and Endurance builds. Iron Flesh expires quickly. Gwyn's attacks decrease Stamina quickly and make it difficult to counter except with Parry/riposte.
Flash Sweat, on the other hand, greatly reduces the fire blast damage when he grabs you (another weakness of the Iron Flesh tank) and lasts longer. In conjunction with the Ring of Steel Protection, Flash Sweat makes HP losses tolerable.
Summon / Co-op / Solaire
Surrounding him from opposite sides causes Gwyn to slow down because he turns to face the player he will attack before initiating the attack. When one player fires arrows at him, he jumps back and forth and does not attack. This allows the other player to melee Gwyn as he lands from his jump. Saving Solaire of Astora in Lost Izalith allows you to summon him for this fight. Use Solaire as a decoy while you attack Gwyn.
Parry / Riposte
Most, if not all, of Gwyn's melee attacks can be parried, with the exception of the exploding hand grab. Learn to Parry, and you'll take care of Gwyn without a problem.
Parrying is easier using the Target Shield because it has a larger timeframe for parrying than most shields (especially shields in the "Normal Shield" category). Equip your strongest weapon in your right hand, and the Hornet Ring to increase the damage of your riposte after a successful parry. It is vital to keep your equip burden under 25% of maximum to be able to roll properly under Gwyn's swings. When you are a bit farther than his sword's reach, or drinking Estus, he can run at you and stab you with a straight thrust. You need to roll sideways to avoid this most of the time, since the sword's hitbox will still be there after it stops. Getting distance after a riposte can aggravate Gwyn to do a jumping slash, which is easier to parry than a swing combo, because it's slower and you don't need to approach him to parry.
Each of Gwyn's different attacks requires a different parrying time, each attack is difficult to predict. However, Gwyn's lunging attack is not only easy to time, but it's also easy to bait; after each riposte, just distance yourself as far as possible.
No Parry Melee
This takes time, since you'll be able to slip in only one or two hits at a time. Your best chance to get hits is to stay out of the range of his 3-hit and 4-hit combo, since those attacks will most likely drain all of your stamina when blocked. Then, try to bait him to use the kick/grab attack. You can try to punish him after the kick, but be wary of the grab since he will lunge forward a bit to catch you. After the grab misses you can punish him some more.
If you are too far away from him, he will try to leap you, but it is easy to dodge, and then you can roll under it and hit him again. Keep repeating this, until you finally get him.
A shield with high stability and fire defense is useful. Black Knight Shield is the best overall in terms of weight, stability and fire resistance. The Dragon Crest Shield has excellent fire resistance but lower stability (upgrading is advised).
Putting the pillars in the middle of the room to between yourself and Gwyn gives you time to heal and regain stamina.
After you traverse the white fog, block or parry/riposte Gwyn's first attack, then go behind the last pillar on the left (when the entrance is behind you). This pillar is the only one big enough for this tactic. When Gwyn attacks you, start turning clockwise. Use a stabbing weapon and wait for his grab attack. Only attack, heal, or regen after Gwyn misses with his grab attack and do not be greedy. While turning, try changing the distance between you and the pillar according to Gwyn's actions because his blade can pass through the pillar. Don't get too far away, because you want to keep Gwyn behind the pillar and not in front of you.
No Parry Melee + Pillar Defensive Strategy Combination
All you need to do for this one is to have a high stability shield, preferably a greatshield like the Greatshield of Artorias or the Black Iron Greatshield (upgraded to +15 or the highest you can upgrade it to for higher stability) and probably a stamina regen item (mask of child or cloranthy ring). Find a spiked stalagmite that's disleveled that's on the right side of the fog wall to use as your environment to fight Gwyn. Hold guard on all his attacks with your greatshield, you'll only take small amounts of damage and your stamina bar will be barely fazed. Stop holding guard in between attacks if you can, to make your stamina regen faster. After he does his 3 hit combo (with the last hit being a strong vertical attack) or his 4 hit combo, you can attack one time (or two, depends on the speed of your weapon, I used a greatsword). To heal, circle around the stalagmite until you are facing the other direction of Gywn and he loses sight of you (he will start looking around for you). You should have enough time to use your estus once before he finds you, so hold the guard button while mid-estus. When he grabs, dodge roll back, attack him once and then go back to guarding. He will usually grab right after he kicks you for turtling under your shield so be prepared. I used this strategy in NG+ and it worked pretty well. Manage your estus flask count wisely though, this will take time and you will lose a few bits of hp each time you guard.
Pillar Spear Strategy
When you go through the fog gate run to your left towards the rock formation. Stay on one side of this and rotate as needed keeping Gwyn on the opposite end. Strike out with your spear when he is close to the middle mound/rock. Using a Spear, when you strike the rock it actually damages Gwyn if he is close enough, on average for every 3 thrusts 2 will hit. When he is directly opposite you and takes a backstep, take a backstep yourself and quickly heal if you need to. Using this strategy it can take 40-50 hits. If you're having trouble, try to rotate and keep him slightly to your right so you can strike at him. This is a little riskier.
If executed properly, this should completely nullify his grab attack. If he does grab you and throw you, quickly run back to the rock and wait for your opportunity to heal before going back to the plan. Just be patient and keep hacking away at that rock.
This fight goes quickly using Pyromancies assuming Crown of Dusk and Bellowing Dragoncrest Ring are equipped. With a fully upgraded flame, you should be able to do around 800 damage a hit with Great Chaos Fireball / Great Fireball. Four direct hits will basically end him.
Using Pyromancies in conjunction with the pillar strategy is also effective. Cast Great Fireball or Great Chaos Fireball while he is coming around the pillar and he will walk into it. Great Combustion works better as a counter than a melee weapon because it is almost incapable of interruption and doesn't use Stamina.
If you have multiple Fire Tempest from previous playthroughs, then just run to the right hand pillar on the sides, as you enter the battle. Hide behind it and cast it. When Gywn doesn't do an attack he dodges to the side. If you can hit him and make him dodge, he'll hit the other fire columns.
Much like above strategy equip items that boost your magic damage. It seems that when using Combustion, Gwyn will try to dodge to the side to avoid follow-up attacks. You can use this to your advantage by simply locking on to Gwyn, blocking his very first jumping attack and following it up with Great Combustion. Hit him to make him dodge, and then punish him during his post-dodge inability to act. This makes the fight ridiculously easy as you can basically just spam Great Combustion until he falls. In NG it takes 6 Great Combustion with Crown of Dusk, Bellowing Dragoncrest Ring and a fully upgraded Pyromancy Flame. (This strategy probably needs testing to determine if it always works or if triggering his dodging is either damage or luck based.)
Magic - Homing Crystal Soulmass
Wear medium or light armor in order to dodge Gwyn's lunging attacks. Equip the Bellowing Dragoncrest Ring, Crown of the Dark Sun, and the Tin Crystallization Catalyst to enhance your sorcery damage. Gwyn tries to stay within close melee range, which limits the use of many sorceries. As Gwyn tends to jump sideways when you cast a spell while locked onto him, this can be abused. Lock on, and every time you cast Homing Crystal Soulmass he will jump, interrupting his attack sequence and allowing your spell to hit him directly afterwards. This stuns him long enough to recast HCS.
Magic - soul spear / Solaire Decoy
This is recommended for pure magic builds, wear light weight armor, and a sheild with decent fire defense and stability. Dragon Crest Shield, or Black knight shield. Save Solaire in Lost Izalith, summon him for the fight. Upon entering the fog gate get near the first pillar, dodge, roll whatever you have to do to stay alive until Solaire starts hammering away at Gwyn. Stand a decent distance away and just fire away, on new game you can down gwyn in about 6-8 shots depending on your intelligence and magic adj, and if he dodges your magic or not.
Equip the Greatshield of Artorias, Fire Avelyn +10 with simple Wooden Bolts, and the Dark Wood Grain Ring. At nearly 200 damage per attack animation, this takes some time. Two successful shots will stagger Gwyn, allowing you ample time to recover HP etc. Go in, block Gwyn's leaping attack, back up some and wait for him to start his combo. As you see him start his second swing, fire your Avelyn.
After defeating Gwyn, you get to choose an Ending. Lighting the bonfire unlocks the To Link the Fire ending, while walking out to where the fog gate was unlocks the Dark Lord ending. There are no prerequisites for either ending.