Oblivion:Knights of the White Stallion (quest)

Quick Walkthrough
# Talk to Count Marius Caro about a dangerous bandit.
# Speak with Mazoga for more information.
# Travel with Mazoga to Telepe and kill all the bandits.
# Report to Marius.
# Return Black Bows to Marius for a bounty.

Detailed Walkthrough
The Target
Speak to Count Marius Caro after completing Mazoga the Orc's quest to begin this quest. The Count wants you to kill an Orc outlaw named Black Brugo, chieftain of the Black Bow Bandits. He'll suggest speaking with Mazoga, who may have contacts with outlaws due to her shadowy past.

Speak with Mazoga and you'll learn that she knows Brugo, that his hideout is an Ayleid ruin west of Leyawiin called Telepe, and that he visits there between midnight and 6am (see Notes). Keep in mind, he may arrive early; sometimes shortly after 8pm. Mazoga will wait in the Castle Hall until you ask her to follow you.

The Black Bow Bandits
Travel to Telepe (northwest of Leyawiin and a short distance southwest of the White Stallion Lodge) and kill Black Brugo and his gang. The ruins are quite small and contain two of Brugo's henchmen. Brugo and his friends Alonzo and Roxy Aric are located nearby after you enter the cell if you arrive at the time indicated above, so the action begins quickly. They will enter the ruin, however.

If you arrive at 8am or shortly afterwards, you will see Brugo, Alonzo, and an invisible Roxy Aric heading out to the ambush site a bit north of Telepe near the road. This offers new tactics; as long as you walk behind them, they don't attack until arriving at the ambush site (even if they shout alarm phrases), so you can fight them  one at a time, making the fight a lot easier.

After killing Brugo, be sure to take the key that he carries. It unlocks an Ayleid Coffer in Telepe containing 300 gold and a quest-related note which you would otherwise have to pick open.

After the battle, Mazoga is quite excited that she'll soon be a real knight, even though she apparently does not know how to be one or even what a knight-errant is, and says she'll meet you in the Castle Hall. Note that, before she starts traveling on her own, you will first have to lead her outside and away from the ruins.

Become a Knight
Report to Marius to become a Knight-Errant of the Knights of the White Stallion, receive a Leyawiin guard's shield and the key to White Stallion Lodge. He also promises a bounty of 100 gold for every Black Bow you deliver to him.

If you speak to Mazoga after this, she will tell you that she will be at the White Stallion Lodge, after which she leaves the Castle Hall and then Leyawiin itself.

After the quest, Mazoga will say "I'm gonna go get me some black bows. Tag along if you like."  This initiates the freeform quest Black Bow Bandits.

Notes
The black bows you retrieve from the bandits are quite good and you won't find better bows until Dwarven bows appear at level 6. If you are into archery you might want to keep one for yourself, at least until you find better equipment. Also remember that the count will pay you more for black bows (100 gold) than any merchant (base price is 70 gold).
If you do not need the help, you can speak to Mazoga and ask her to wait for you to ensure her survival. If you tell Mazoga to wait while on route to Telepe, and continue on your own, you may have trouble finding her again later unless you set a blue map marker at her location - it may be best to leave her inside the Leyawiin castle. The count will still make her a knight together with you, even though she did not really do anything.
If Mazoga gets killed while in the ruins, it will not affect the outcome of the quest. Once you complete the quest, the messenger from Marius apparently feels happy in depositing the shield and keys on her corpse. You can go back to the cave and pick them up yourself, along with her armor.
Initially, Mazoga will confusingly tell you that Brugo will be at Telepe every night, then when asked any time afterwards, will indicate that Brugo will be there on Middas.
Mazoga has a minimum level of 10. If you do this quest early at a low level, Mazoga can do most of the work for you without having to worry about dying.
Sometimes, the standard bandit guarding Telepe will stand on the hard-to-reach section above the entrance. To get to top of the entrance, jump on one of the low rocks at the back of the building, then carefully jump to a slightly higher ledge nearby, and keep going until you reach the top.
Killing Black Brugo can be remarkably easy. Simply don't push the switch to open up the gate he's behind then using a bow just shoot him until he dies.  He will run around a bit but still stay within the open circle area of the gate for you to shoot him.

Bugs
 
To resolve the issue, open the gate manually if Brugo hasn't done so already and leave the dungeon. Wait one hour or longer and he should resume his normal schedule.
 

Journal Entries