She will summon skeleton spirits and they can cast health regen buff. So you need to kill the spirit ASAP

As a blade character my strategy for killing nayda is focus the iron golem down first avoiding nayda's water torrents. After that I will usually be around 30% health. Killing her summons regains my health by 12% each time so I can usually just focus her avoiding the water torrents and spin to win with bladestorm.

Hello, as a Mage, I have some advices to beat the Boss.

1. After entering the room, eat the Tyche Seed.
You can get Tyche Seeds at the Spirit Maker's Lodge, every time when you login. He will increase your health and mana by 50% and will make it easy to keep your mana. But you should pay attention to keep your health because you need to wait for 60s to use Health Potions again.

2. Take some Mana Potions.
The Mana Potion's CD is 60s, same to that of Health Potions, but you can use them separately. When you need mana immediately, for example to cast "Magic Shield", the Mana Potion will help you.

3. Use "Cold Glaive" and "Frost Bloom"
In my opinion, "Cold Glaive" and "Frost Bloom" are the simplest solution to kill Nayda when you don't have enough Cast Time. The stategy is very simple. Just cast Frost Bloom and throw cold glaives while running around Nayda, without a pause.
When I got Nayda for the first time, I dealed like this. As "Cold Glaive" doesn't have a so much higher damage rate, you need a time to kill Nayda, but it is AoE and you can kill skeleton spirits at the same time... probably.

(4. If possible, use Gio' Gan
It increases your damage by 15%. We don't need the explication for its efficacy!)

Anyway, good luck.

Hey, where I can find Spirit Maker's Lodge ?

She asks you to bring her skull kell where to find it ?

The skull is next to her, at the house.

Spirit maker lodge is at the top of the map, you need to cross a wooden bridge high up. One skill for blades that makes her very easy is shockwave move after completing bladestorm before it. It will silence her for 6 seconds with a CD of 20 seconds. It can keep her from spamming water torrent on you and give you ample time to kill the golem fast. And like they said if you are short on health potions, just grab a couple fruit from the spirit lodge. 4 of them should be more than enough for melee. Just watch your health and get out of the water torrents if she spawns them on you, cause you'll need another 60 seconds until you can use another healing item.