A huge red dragon that is guarding the bridge to Altar of Sunlight in the Undead Burg. He is more powerful than most bosses in the game, and his attacks are relentless and ruthless. Though the player has to pass that bridge at least partially to advance, it is not necessary to kill off this dragon to complete the game.
First, he'll show himself at a small bridge just before you reach the first bonfire, from which he'll fly to the gate guarding the Altar of Sunlight. He'll stay at the gate until killed or the Bonfire is reached which is under the dragon.
Drake Sword - do enough damage (about 200) to his tail. When the necessary damage has been reached, the sword will be automatically added to your inventory.
- The dragon heals when his HP drop below 50%, signified by him covering himself with his wings and will not attack. The healing process is slow, so you can pass safely beneath the dragon to access the altar.
- When you get to the Sunlight Altar without killing him, he'll fly away. But he will not disappear forever. Upon returning, he may or may not be present.
Strategy for Skipping the Dragon
You can access the Sunlight Altar without killing the Hellkite Dragon.
Without Master Key, no bow
There are 2 walls on each side of the bridge which provide cover from the dragon's breath. If you can run past the Undead Soldiers and hug the wall on either side FACING the dragon, you will be spared from flaming death. The Undead Soldiers will die from the attack so they are of no concern. All you have to do now is wait, while keeping an eye on the dragon. Make sure you hug the wall's left/right most part. After some time with you behind cover, the dragon will hop down onto the bridge; this is your immediate cue to run as fast as you can. The key is timing in this one; before the dragon leaps from the tower to the bridge, it will let out a snarl of a sort which indicates it is about to leap to the bridge (1 second gap between snarl and leap). As soon as it leaps, run towards the tower and if you're quick enough, you will be inside the tower before it can turn to face you. If not, chances are you'll be hit by the fire and cut a whole chunk of HP from you. The fire itself is survivable as long as you are far enough but if you do get hit and survive, make a break for it and run into the tower as soon as possible.
As soon as you enter the tower, make sure you go to your right, towards the balcony with the passive Hollows. After some time, the dragon will leave and you'll be free to pull the lever leading to the Undead Parish.
Without Master Key, with bow
If you can get the dragon to begin healing himself there is ample time to run beneath. You can hide beneath the stairs. And fire a bow upwards. When the dragon begins flying back and forth just shoot wildly into the open space. The arrows will hit the dragon about as fast as you can shoot them and rarely miss. The flames may graze you if you get too close. The damage will most likely be negligible. If not, consider coming back after you are able to take more damage.
With Master Key
When starting a New Game, pick Thief class or the Master Key starting gift. Basically, what you're going to do is avoid triggering the dragon's initial appearance and enter the Undead Parish backwards.
From Firelink Shrine, go down to New Londo Ruins. Open the locked door to the Valley of Drakes with the Master Key. Run past the Undead Dragon and two Drakes, then enter the elevator to the Darkroot Basin. After the bonfire, run past the Halberd Black Knight, then the go up the cliff until you reach the Darkroot Garden. Go left (then right after the Demonic Foliage) into the building with the Titanite Demon, exit to the Undead Parish. From here, backtrack to the dragon's bridge. He won't be there, so you can safely loot the Claymore, open the Sunlight Altar gate, and activate the shortcut to the Undead Burg.
If you want to make him appear at the bridge, go to the beginning of the short bridge in the Undead Burg. Triggering his appearance there will allow him to spawn at the bridge.
Strategy for Killing the Dragon
For first time players, it is highly recommended to avoid attacking this dragon until you've leveled up a bit, although you should still try to get the Drake Sword by shooting off his tail which can be done safely with just a few arrows.
- Remember that the dragon can regenerate himself when his HP drop below half, so your damage-per-second must be able to overcome his regeneration. In NG, a bow damage of about 50 per shot can overcome his HP regeneration if you shoot consistent enough.
- You can use any bow (or greatbow) with any arrow (even Wooden Arrow) to kill him. Obviously, the higher the damage per shot, the better.
- 50 Dragonslayer Arrows with a greatbow is enough to kill him in NG. You can even kill him fast enough without him ever regenerating.
- For weaker bow & arrow combinations, you may need to bring more arrows, as you may trigger his HP regeneration, effectively increasing the HP damage needed to kill him. If you're doing 50 damage per shot in NG, 100 of any arrow should be more than enough to kill him, even if he's regenerating.
- Try levelling up your Strength/Dexterity or upgrading the bow first if you think you can't do it consistently, to make room for errors.
- Equip Hawk Ring to be able to shoot him from longer range. The farther you are from him, the more time you have to escape from his fire. If you use Composite Bow, the Hawk Ring may be mandatory to use because of its short range.
- Equip Red Tearstone Ring to boost damage. Especially useful if you shoot from under the bridge, as you are in no risk to get damaged.
- 3 places to shoot him from. Clear the enemies first and learn the timing.
- The bridge - easier to target (and can get headshots) but you need to be quick on your feet. Shoot him not only when he's landing or perching, but also when he's moving, getting down from his perch, and jumping up to his perch.
- Under the bridge, near the sword-wielding Undead Soldier - 100% safe, but much smaller target, mostly the wings and tail. This is the preferred place to shoot him from if you just want to get the Drake Sword. Aim at the upper part of his tail instead of the tip (it's easier this way). He'll hop to the bridge, swinging his tail to your right side. Without getting out of aiming mode, move your reticle to the right, his tail will enter your line of sight. Shoot his tail here too (usually only enough for 1 shot, though) before he's back to his perch.
- Under the bridge, near the door to the Small Undead Rats - 100% safe, even smaller target, but can get headshots. When you shoot from here, always start with a headshot. Then, you can get several shots (1-2 with greatbows, potentially even more with normal bows) when he hop to the bridge and back to his perch.
Probably one of the easiest ways to kill the dragon, depending on whether or not you've upgraded the Crossbow. Upgrade it to 15 if possible. You can use Wood Bolts, but obviously the stronger the ammunition, the better.
Stand under the bridge as you would if you were just going to shoot its tail with the bow. Aim slightly above the dragon's body to accommodate distance. You can use the Binoculars to make aiming easier, although not necessary.
- Equip the best catalyst/talisman for your Intelligence/Faith range and spell damage-boosting equipments (i.e. Dusk Crown Ring and Bellowing Dragoncrest Ring if you're using sorceries, or Ring of the Sun's Firstborn if you're using miracles).
- You can use any arrow-type spells, but the higher the damage with one hit, the better. Bring multiple copies if you think it's not enough.
- From the entrance to the bottom of the tower (between the three Small Undead Rats and the spear Undead Soldier, look up to the dragon. Your lock can't reach him, but your spell can. Adjust the camera, try a few shots to get the right angle (preferably with Soul Arrows). For every hit, he will get down to the bridge, then back to the perch immediately because he didn't find any target. Repeat until he dies.
- Either go full Fire-resistant heavy, or go unarmored. Middle-weights will only get killed because the flame is too strong for medium armors, while the weight makes rolling not fast enough to roll to safety. You won't need a shield because you'll be two-handing your weapon and blocking the flames will only get you stun-locked to death.
- Full armor: Black Iron Set +5, Flame Stoneplate Ring, Flash Sweat pyromancy (this cuts the fire damage greatly).
- Light armor: Havel's Ring to offset heavier weapons. Dark Wood Grain Ring also helps as you can roll a little bit faster than normal fast rolls. Use weapons that have a reasonably fast attacking speed, not ultra greatswords or great hammers.
- You can damage the dragon first with arrows until his HP is near 50% to make the melee easier. You don't need strong bow and arrows because the purpose is not to overcome his HP regeneration.
- At the top of the stairs, on the right (assuming facing dragon) side, running all the way forward to the rail is a safe spot against the dragon flames when they're breathed from the front. Moving backwards from that spot to the wall is a safe spot against the rear flames. Moving between these two spots avoids the horizontal bridge flames, and it is close enough to the stairs that one can roll down them and avoid the overhead flame move.
- For light armors: Once the dragon has been lured with a bow shot, it will breathe flame and then will take 4-6 steps forward onto the bridge. Wait until a talon is exposed then hit the claw from a position just above the stairs with a 2-hander or you can attack his head with 2-handed attacks (even with heavy weapons) as soon as he landed, when he's still in the "landing" animation. Then quickly retreat down the steps to avoid the overhead flame. After the overhead flame, let him take about 3 steps and then run back up. If you don't, the dragon will fly back to his perch and potentially heal himself. If you run back up too soon, he'll do another overhead flame, so you need to be careful here. If your timing was about right, he'll return to his horizontal flame + walking on bridge pattern. Repeat with two handed attacks to the claw until he dies. Be wary that there's very little time between your strike and his retaliatory flames.
- For full armors: You can challenge the dragon directly after luring him to the bridge, as the armor's physical resistance and Poise will take care of the claw attack, while the high Fire resistance in addition to Flash Sweat will make the flames do insignificant damage. Just remember not to fight the dragon when the Flash Sweat expires.
In ng+ the hellkite dragon's regen will far out pace any ranged damage you can do to him (tested with Dragon slayer great bow + 5 with 76 dex. 50 str and gough's great arrows) and killing him with melee is difficult due to the sporadic nature of his overhead flame attack whilst on the bridge. Equip the Tin Crystallization Catalyst, the bellowing dragon crest ring and the crown of dusk to maximize your magic damage. First whittle his hp away with a bow until he is roughly at 40-50% hp then go to the safe spot right ahead of the staircase and cast homing crystal soul mass. Make sure not to let the projectiles hit the walls. Switch to your most powerful weapon and two hand it. Eventually the dragon will land, when he does rush toward him and make sure that none of the projectiles detonate on the walls. If the soul masses don't kill him strong attack him a few times and he should die.
Another tactic on NG+ is to trigger his landing, either by shooting him directly, or comming out on the bridge (For fire breath) and waiting afterwards. When landed, rush next to his left leg and attack it 3-4 times, fire breath comes after, and the moment it's over, rush back downstairs. Wait for him to return on the roof, and trigger his landing again. Repeat 4-5 times, depending on the weapon, and victory is yours.