Krosis

Krosis is one of 8 named Dragon Priests of Skyrim. His name means "Sorrow" in the Dragon Language. He is found at Shearpoint in the company of a dragon.

Krosis emerges from a sarcophagus in front of a word wall once the player approaches and is within target distance. He uses Wards and carries a Staff of Fireballs. Like all Dragon Priests, he can also turn your summoned creatures against you and can summon a Frost Atronach. He is immensely powerful, so lower level players should be cautious. Once defeated he will drop the Krosis Mask.

Strategies

 * Provided that you have high Sneak, One-Handed, a good Dagger, and the perk Assassin's Blade, you can sneak behind Krosis and attack with 15x Damage Sneak Attacks. Krosis should go down in about 3-7 hits. This is much more riskier as even with a high sneak, as you could still be detected.
 * You can bring Shadowmere (as she is very strong and can take many hits) and J'zargo (he favors the Shock Spell, so he should be able to deplete Krosis's magicka quickly) to distract Krosis while you attack.
 * Another strategy to defeat him is to flee to the nearby Giant camp, and lead him towards the mammoths and giants so they attack him. Fire projectiles from a distance and he will fall in no time (be careful on attacking the Giants and Mammoths as they might all turn around and attack you).
 * Having a good melee character and a high armor rating, you can attack Krosis with a series of power attacks and the using Unrelenting Force to make him stagger (using an enchanted weapon that drains magicka will make this much easier as Krosis does not have melee attacks). Be prepared and save before fighting.
 * You can use Unrelenting Force and push Krosis off the cliff. You can then peek over the ledge and fire projectiles at him (having a high Archery will make this much faster).
 * You can hide behind the Word Wall and attack Krosis from there. Be sure to take cover when Krosis uses spells to avoid taking damage (again, having a high Archery will make this much faster).
 * Having the Atronach Stone on may simply take the pounding from Krosis, with a healing spell in one hand regenerating the same, if not more, than the health lost (assuming your Restoration skill is high enough). You can then use the other hand to attack Krosis. Being a Breton will extremely be beneficial.
 * Strategic use of Wards in one hand and a weapon/spell in another will make killing Krosis easier.
 * You can use the Call Dragon shout to help you defeat Krosis. Not recommended for players who want to defeat Krosis earlier as the Call Dragon shout is unlocked duing Act III.

Items Dropped

 * Bone Meal (1)
 * Gold (100 - 2000)
 * Krosis (Mask) - 20% bonus to Lockpicking, Archery and Alchemy
 * Staff of Fireballs

Bugs

 * Sometimes if you get close to Krosis fast enough when he gets out of its coffin, there's a chance that Krosis won't attack you at all (assuming you maintain the same distance).