According to the Skyrim Legendary Edition Prima Official Guide... Zahkriisos' health is actually 2000, along with the other two Acolyte dragon priests.
Zahkriisos' abilities, along with the surrounding environment, makes fighting him a different experience than most other dragon priests. From a distance, Zahkrilsos employs Lightning Storm to attack. One tactic for defeating him is to summon a Storm Atronach, as he will attempt to get rid of the atronach before anything else. As he is a shock-based priest, the atronach resists all of his attacks, thus leaving him and his summons vulnerable to attacks. As is conventional with enemy targeting, if the summoner is closer to the enemy than a summon construct, the enemy attacks the summoner instead.
The water surrounding Zahkriisos' tomb is deep enough that it triggers the swimming animation; since he tends to hover above the water when attacking or defending, melee attacks are essentially useless here - though it is possible for the persevering warrior to force Zahkriisos against the non-submerged walls of the chamber. Longer-range bows and spells, on the other hand, are not only more effective, but the appropriate perks can stagger Zahkriisos, leaving him unable to use his spells.
The Whirlwind Sprint shout allows for him to be reached quickly. Alternatively, the Become Ethereal shout provides total invulnerability to his attacks for a time, allowing for a moment of recuperation if heavy damage has been sustained.
There are a few Potions of Waterwalking scattered around the previous parts of the dungeon, which can be very useful when fighting Zahkriisos. Ahzidal's Boots of Waterwalking proves useful in the same way.
This battle is uniquely challenging among battles with Dragon Priests . In most battles, players find that the Dragon Priest constantly floats away from arms reach, thus may be difficult for warriors. In this case, there is a large body of water that Zahkriisos can float over. Warriors can use the Bloodskal Blade to reach him, but they may find it difficult, otherwise use a water walking perk or spell to reach him.
Mages will have no problem reaching him, for the room is large, but they should be well aware that Zahkriisos is using one of the most powerful spells (Lightning Storm ), and he is resistant to shock 25%. The best, and fastest way to defeat him is to chase him into a wall, where he cannot back away, and to work from there.
Due to his annoying habit for conjuring Seekers, who also water walk, the player must prepare for a difficult battle.
Like with all Dragon Priests, Slow Time is extremely effective on Zahkriisos, since he won't have time to flee, and one will be able to put as many blows as they desire until the effect wears off.
Easy Zahkriisos Fight w/ Glitching Edit
- Before entering the mines, be sure to grab a platter (or a wooden plate).
- Proceed through the dungeon normally until you reach Zahkriisos. Awaken the dragon priest and remain hidden.
- Return to the now closed gate.
- Facing the gate, follow the wall on your left until you pass the second pillar. At this section of the wall, between the second pillar and the third pillar (the third has candles at its base), you want to use your platter (or wooden plate) to clip through the wall.
- After clipping through, you should land in water. Swim outside the block of water so that you start falling, and allow yourself to fall into the void.
- After the fall, you should reappear back at the beginning of the mine. Proceed back to the closed gate just before Zahkriisos and open it.
- Lure Zahkriisos back to the hallway with the swinging traps and let him get hit by them. He should die after a couple hits and you can then loot his mask and continue on with your game.