Scorpioness Najka. How to beat her? Quite easy.
Upon entering the area, you’ll see her submerged in the sand. She’ll hit you with some projectile attacks. Those are quite slow, so just avoid them by running around her. Time her attacks, which are, quite predictable, and strike her. She’ll dive under the sand, and after some time, she will jump out of it. Don’t get spooked though, her attacks are not that hard to avoid.
Scorpioness Najka lacks mobility. Her melee attacks are quite slow, so without hesitation, strike when you’ll see an opening. Don’t rush to destroy her, take your time, but keep in mind, that compared to the other Dark Soul II bosses, this is one is relatively easy. So, you know, you don’t have to be that afraid of her. Just avoid her attacks and you’ll be all right. Upon failing to deliver her tail-sting attack, Scorpioness Najka will be stuck/frozen for a moment. Strike her a couple of times during that pause.
After some time, Scorpioness Najka will burrow under the sand. That’s where you’ll have to be more careful. Run the concrete slab, so as to avoid her burrow attack. That one does massive damage, so be alert, whenever you see her burying herself under the sand. After that, she’ll return to the surface to deliver her melee attacks.
Don’t get too far from her, as she might use her magic attacks. Those are a bit harder to avoid. But if it happens, just sprint away. Keep doing that, until she stops. That’s where you come back, and await for her slow stinger attacks.
Keep in mind, that her front fangs act as a shield. So when the moment comes, try to hit her in her sides, where Scorpioness Najka is the most vulnerable. Avoid hitting her tail, as she might use a sweeping attack and you’ll lose the momentum.
That’s it. Just keep your head cool and watch the Scorpioness Najka attacks. Which are, quite predictable, so you’ll be okay. When the moment comes, strike her enough times and you’ll beat her without breaking that much sweat.