Nashandra

Nashandra is the final boss and main antagonist of Dark Souls II.

Location
Throne Of Want, after defeating the Throne Watcher and Defender, and having the Giant's Kinship in your possession.

You will also need the King's Ring to open the King's Gate to get to Nashandra.

Description
A tall humanoid creature wielding a long scythe in her right hand. Her left hand emanates a purple light that can become an energy beam or cause an explosion when she puts it near her chest. Her legs are covered by a skirt made of a black goo filled with bones. She can also summon four black fountains that curse those who stand near them. She can speak and can change into a more human, yet still gigantic, form.

Lore
Nashandra originated as a small fragment of Manus, Father of the Abyss. When Manus was defeated, he was reborn as many fragments varying in sizes. The smallest fragment sensed its own fragility. For this reason, it was the first to become conscious and started to want what it did not have, possibly power and size. This small fragment increased in power, until it became the one known as Nashandra.

Nashandra seduced  Vendrick  and convinced him to cross the sea and steal a certain object from the giants, which in turn caused the creation of the golems, who built   Drangleic Castle. Drangleic went into a Dark-like peace. After an unknown time period, the giants sieged Drangleic and had nearly destroyed the kingdom when they were defeated by an unknown hero (implied to be the player him/herself), but the kingdom fell into ruin nonetheless, she later inherited the throne when the old king went Hollow hence her statement directed at us in Drangleic Castle, that there only can be one ruler. There, she covets the First Flame and the Great Soul.

Strategy
Nashandra specializes in dark magic and will immediately summon four Curse "fountains" once the battle starts. She has two methods of attack in addition to inflicting Curse on your character and eating away at his/her HP:

Scythe: She will swing her scythe sideways one, two, or three times (the third having a slightly longer windup and dealing heavy stamina damage on block), or do an overhead swing with a long recovery time. Her scythe swings can easily stagger characters with low adaptability and poise. Rolling diagonally backwards is the most effective way at dodging both of these attacks when close to her.

Dark Magic: She will either fire a beam that starts on the floor close to her and emits outward from the floor vertically, which can easily be avoided by strafing, or execute a small AoE attack similar to Wrath of the Gods. If she begins casting and her body is not being covered in dark energy, then she will use the beam; otherwise, it's the AoE attack and you must back away. If you look closely, you will also notice that her hand movement is different for each attack (she draws her hand close to her chest when using Wrath of the Gods). She also has another type of beam which sweeps horizontally, so be aware of the direction of the beams as these beams are usually fatal when combined with the health drain.

For melee characters it is also possible to equip light armor and dodge her attacks, ignoring the Curse buildup and only healing when your health starts draining. Also a good method for melee users is to wait at a distance for her to come towards the player, baiting her away from the four curse fountains. The curse fountains can be broken stopping the curse build up and health drain.

Summoning help will make the fight easier, even if it's only the two NPCs Vengarl of Forossa and Benhart of Jugo, as they will draw attention, leaving you with a good amount of room to deal damage and heal as needed.

Pyromancy is effective against Nashandra.

Attacks
Curse Fountains: Summons several white fountains that build up your curse meter. Can be destroyed in one hit

Laser Beam: Her hand fills with darkness and fires a beam at the player

Dark Explosion: Her hand fills with darkness, but she puts it closer to her chest and her whole body starts being covered in darkness then releases an AoE dark attack, simialar to Wrath of the Gods (Dark Souls II)

Overhead Strike: Performs an overhead attack with her scythe.

Swings: Swings her scythe twice in a row.