Ninianne of the Lake is one of the mini-bosses added with the Genshin Impact version 4.0 update. This elemental creature has a model similar to the ordinary Hydro Mimic but much stronger. 

How to Find Ninianne of the Lake 

The mob is located in the northern part of Boreas, near the map's border. To start the battle, simply approach the boss - it will react to the Traveler and immediately begin to attack. There's no need to unlock or wait for the boss's appearance - it appears in Fontaine right away, even without activating the Statue of The Seven Archons. 

How to Defeat Ninianne of the Lake

Ninianne, being an elemental creature, is immune to Hydro damage and constantly has the "Wet" status. 

How to quickly defeat the boss:

- Include characters of different elements in your party: Dendro, Pyro, Electro. Hydro mobs are particularly susceptible to reactions like Vaporize, Overloaded, and Burning;

- Stock up on healing items for HP recovery;

- Utilize both healers and characters with shields. 

Ninianne has two powerful attacks: a ground shockwave and a swirling strike. Even with shields and healing, try to dodge the mob's attacks - they are very strong, easily break through defenses, and can "one-shot" a character with low HP. 

For defeating the boss, you will receive the achievement "Ninianne of the Lake" and 5 Primogems.