Skyrim Secondaries- Forbidden Legends: Mikrul Gauldurson

Through the door to the Crypt, you'll find yourself at the base of some stone stairs.  Ascend very carefully, as there is no door at all separating the small hallway and its Potion of Vigorous Healing from the main crypt chamber.

What awaits you here is a devastatingly hard fight if you're below about level 25.  Your entry provokes Mikrul Gauldurson to emerge from his crypt as a powerful draugr- he not only has some mystical abilities, but the one-handed blade he wields has a life-leeching enchantment on it of considerable power.  This means that you can't let him hit you very much, or he's going to heal off all the damage you try to cause him.  Followers without strong defenses can be a liability because of this, even if they do give you a chance to stand back and plug him with arrows.  Just to make things more harrowing, the sarcophogi lining the room will release a steady, if slow, stream of unarmed draugr to claw at your back as you try to take down their leader.

Ranged attackers and characters who are using shields to defend themselves will have the easiest time here, as they can do considerable damage to Mikrul without him getting a chance to heal very often.  Melee fighters have to be more powerful, and deal as much damage as possible with every hit lest it become an endurance match- Mikrul's sword will always win him an endurance match.

If you need to, don't be afraid to use the terrain here to your advantage- leaping from sarcophagus to sarcophagus or outcropping to outcropping can save you a lot of hits, as there's very little to worry about at range here.  Also be sure you focus your damage on Mikrul, as the thralls will all die instantly once he does.

Amusingly, fleeing out the door will bring Mikrul after you, thus stemming the tide of minions he has at his disposal and making things much less dangerous if you're having problems.