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 also casts Frost Cloak upon himself, which will swiftly drain your stamina if you are attempting to kill him via melee. He is immensely powerful, so lower level players should be cautious. Once defeated he will drop the Krosis Mask.

Strategies

 * It is possible, using the two stones with about a stones space between them directly south east of the word wall, look just passed the pillar to the two stones beyond it, to glitch Krosis in one of two ways. Both ways required clever use of the edge of the stone. The first is allowing you to shoot him whilst putting the edge of the stone between you and his left side so that his fireballs hit the stone. This tricks Krosis into thinking he is hitting you when he is not. The other way is the same idea with the stone, but Krosis will glitch so that he doesn't think he can see you and will stand still without attacking, but you can still shoot him. A higher archery is suggested, just bring a lot of arrows and be careful that you aren't shooting the stone.
 * 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 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.
 * Using Mehrunes' Razor and savagely attacking the Dragon Priest using light attacks will result in an instant kill. Recommended to save and be extremely prepared.
 * For Destruction mages, the Impact perk makes this fight incredibly easy (as it does most other fights). Dual casting Lightning Bolt will kill Krosis in about 30 shots without allowing him the opportunity to muster any offense in return.
 * A good strategy is to hide behind a rock or anything that blocks the fireballs thrown by Krosis, and shoot arrows towards him. If the player doesn't have a bow or arrows, he or she should use spells that can be used afar. As the object blocks the Fireballs, the player can, if accurate, shoot arrows at Krosis. It can be tricky to get to the place where Krosis would try to attack the player but instead hitting the ground or a boulder, but significantly makes the fight easier. Using the Call of Valor shout, the Dragon Priest focuses on him until he dies, efficiently making it possible for you to attack him without the danger of being hit.
 * You can use Elemental Fury with a decent weapon, such as a Daedric Mace with the boosted attack speed and the heavy damage of the mace you can kill him pretty quick.
 * A good combo to use on Krosis is Dawnbreaker and Spellbreaker as Dawnbreaker deals extra damage to the undead and Spellbreaker acts like a Ward by blocking spells.
 * If you are low level, you can quickly back Krosis into the word wall. He will not attack with fireballs at this close range, and he can't flee. Be prepared with healing potions. You will defeat him and get the shout at the same time.
 * You can also attack Krosis head-on, if you are a high-level (not recommended especially in low-levels). If you do, there is a chance he will glitch and not attack you.
 * Another strategy would be to attack him a bit then run up the mountain a little ways and hide behind rocks. He will not follow you but instead shoot at you. The best part is that it will consider you to have no enemies nearby, thus you can use the wait function and restore everything. Krosis will remain at the same amount of health.
 * Another strategy, is if you have obtained the Beast Form ability, you can become a Werewolf and do light claw attacks as Krosis rises. He will flinch with a power hit, allowing a Cat and Mouse strategy to be used aslong as you can escape his fire ball attacks quickly.

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).
 * When killing the dragon before facing Krosis, and then hiding behind the dragons skeleton may cause Krosis to float back and forth aimlessly, allowing you to shoot him with arrows without being attacked by him. Using a shout on him seems to "reactivate" him, though.
 * Sometimes, if you use the Unrelenting Force shout, or finish Krosis off with an arrow, he may become trapped in amongst the rocks on the cliff, making it impossible for you to loot his body and retrieve the mask.
 * Leaving the Dragonstone and coming back (without acquiring the mask) will make the ash pile of Krosis disappear, making the mask of Krosis unavailable.