A large demon found after returning to the Northern Undead Asylum. This is actually the first demon you see in the game; as you exit your cell at the beginning he can be seen and heard stomping around to your right through the bars in the hallway. You cannot face him during your initial escape from the Asylum, but upon returning if you walk through the area where you fought the Asylum Demon the floor will break open and you will drop down into the Stray Demon's arena below. This boss, while both optional and challenging to low level characters, is valued because of its guaranteed drop of a Titanite Slab (NOTE: as of 12/12/12 the Titanite Slab drop is not guaranteed, I just beat this boss and no drop).
Skip to 5:20:
It is not possible to summon in the Undead Asylum, so you will have to face the Stray Demon by yourself. Despite his superficial similarity to the Asylum Demon you defeated to escape the area originally, the Stray Demon has a large amount of health and very powerful attacks. He does a large amount of damage with his most dangerous attack, an AOE, magic-based red wind attack, so expect to be killed a few times until you get a sense of his attack patterns and AOE range. As his location is close to your arrival point, remember to first take a short detour to rest at one of the Asylum bonfires before tackling him, to avoid the annoyance of respawning in Firelink or elsewhere. After falling down into the Stray Demon's chamber, quickly run around or away from the demon to avoid its attack, and heal yourself if possible.
It is advised to stay behind the demon as much as possible or risk being hit by the demon's AOE magic, which has a large radius. You can block his double melee swings without taking any damage. But both of his red wind attacks will cause damage even if blocked (unless your magic block is really high on your shield) and also often cause a knockdown that usually results in your death. While circling the Stray Demon the best time to attack him is from behind after he has performed his area red wind attack by striking the ground in front of himself with his staff. The area of effect of his red wind attack is large enough to hit you even if you are behind him when it goes off, so a fairly safe pattern is to get behind him, retreat away from him a bit with your shield up as he sets off his red wind attack, and then as soon as the attack is over but before he lifts his staff again immediately run forward and hit his tail or the back of one of his legs with a single attack. Do not attack more than twice at the most, and ideally once if you want to get him stuck in a helpful combat loop. Specifically, if you get the pattern down, it is possible to get him stuck in a pattern where he does not move, but rather continues to strike the ground in front of himself and set off his red wind attack each time you attack him in the tail or the same leg from behind. You can then run forward between each of his attack and strike the same spot from behind with a single attack, whittling him down fairly safely. A weapon with good reach such as a spear or claymore (with its R2 thrust attack) will give you a little extra space and time to attack him between each of his red wind attacks.
He may also fly up in the air in an attempt to land on you, but this attack is fairly easy to avoid and if you're quick to run back to him, you can get in a couple hits on him. This is also the best time to cast magic at the Stray Demon. This process can be long and arduous but it is an easy way of defeating the Stray Demon with little to no damage (other than the fall). The Stray Demon drops 20,000 souls when killed. 40,000 souls in NG+
- Extremely weak Against Bleed (3 hits of a bandit knife or uchigatana make him bleed taking 10% of his health).
- The Lifehunt Scythe is also incredibly effective - two hits (wielded two handed) cut down a massive chunk of his health, even on NG+.
Although it will be a challenge, you can also beat this foe with a Drake Sword (must be able to wield 2-handed). Make sure you fight 2-handed as that will give you more damage output. Considering that you can't block most of its attacks (unless you have a good Magic/Physical shield and high stamina), a shield will prove to be useless. Any soul level is possible as the demon will most likely 1-hit you unless you have a large amount of health. The 20,000 souls will certainly be welcome to any low soul level character and it may take multiple tries, but if you think you can do it, it is certainly worth the amount of time spent.
Pyromancer Strategy: Attune the Iron Flesh spell. Once you fall, run up to him and use the spell. Next, hack away with your top weapon. Feel free to drink an Estus Flask or two while your stamina is regenerating. He's going nowhere so mobility isn't an issue.
- Purchase "fall control" and "Magic Shield" from Griggs in firelink. Once above the Stray Demon cast both on your self, and then fall through the floor. The fall control will keep you at full health once landed and magic shield will protect you against his hits if using a shield. If you have saved this boss for later into the game you may already have "strong magic shield" from the Duke's Archives which would be even better. Using the run straight at him tactic you can use your strongest weapon to begin attacking from behind. If strong magic shield is applied you can even withstand his AOE attacks for quite a while.
- When you return to the Asylum (as you clearly have if you are facing the Stray Demon) it is possible to obtain the Crest Shield. This shield has high magic resistance and using it will make the red wind/explosion attack much less dangerous.
- To safely exit the arena after defeating the boss, walk towards the wall with the iron bars and climb up the ladder situated nearby. You will then be able to roll through the broken bars into the first hallway of the game. Be aware though that if you didn't kill the black knight in the starting room (the one you spawn in at the begining of the game), he might spot you and attack you. That escape ladder will also be inaccessible during the fight while Stray Demon is alive, so plan accordingly.
- If you return to the Asylum only to collect other items, such as the Rusted Iron Ring, Crest Shield, or the Peculiar Doll, you can avoid the Stray Demon by walking around the open area through the vases. If you fall in by accident and are unable to beat him, let him kill you as soon as possible (or warp out); if you die quickly your bloodstain should appear on the floor above near where you fell, rather than down with the Stray Demon.
- For players who have not began as a Thief(and consequently without the Bandit's Knife) - the Morning Star can be acquired by rolling off of the elevator shaft that leads to the Undead Church.It can be two handed by all starting classes and will cause bleed regularly enough to kill Stray Demon quickly. Stray's tail can be "chicken" poked for the 300 bleed damage. Master-Key users can use this to avoid getting the Uchigatana or the Reinforced Club from the Undead Merchant -preventing the Red Dragon from triggering to nest at the bridge and having to fight the Taurus Demon.