Nashandra

You are now ready to take on the final boss.

Drangleic Castle

Rest at the King's Gate bonfire and attune any spells you need for the upcoming boss fight. Crystal Soul Spear is effective against the boss. Equip the King's Ring, head downstairs, and wait in front of the iron gate for it to open. While waiting for the gate to open, equip the Hollow Skin to prevent your character from becoming hollow during the boss fight. Have plenty of Old Radiant Lifegem ready for healing. Elizabeth Mushroom is better, but consuming it would cancel the buffs from a Brightbug.

Nashandra

Sorcerer versus Nashandra NG+7, Dark Souls 2 SotFS

Crystal Soul Spear is effective for a ranged fight. Equip the Magic Clutch Ring and the Blue Dagger to boost your damage output. As soon as you enter the arena, lock onto Nashandra and spam Crystal Soul Spear. You should be able to cast at least four times before the boss summons various dark clouds.

Nashandra is dangerous for two reasons. First, being near her can rapidly build up your character's curse metre and turn your character hollow, and consequently lower your maximum HP. Equip the Hollow Skin to prevent this hollowing effect. Second, Nashandra occasionally summons various dark clouds around her. Being near a dark cloud would rapidly drain your HP. Use a melee weapon to hit a dark cloud to dispel it. As long as you are far away from Nashandra, you should have plenty of opportunities to pop an Old Radiant Lifegem. Heal up, create some distance from Nashandra, and perform one or more casts of Crystal Soul Spear.

The most dangerous attacks are her laser attacks, which comes in two varieties. The first laser attack would aim straight at your character. This is easy to dodge; strafe to the left or right as soon as you see the laser coming at your character. The second laser attack would sweep an arc from your left to your right. Roll to your left as soon as the laser is near your character. If you equip the Blue Dagger and the Magic Clutch Ring, then the laser can one-shot your character. Just before you roll through the sweeping laser attack, swap out the Blue Dagger so your character's left hand is no longer holding the weapon (i.e. press left on the D-pad). Even if your character hits a laser, the effect would not be a one-shot. Dodge the laser, then cast Crystal Soul Spear one or more times.

If your character is up close to Nashandra, the boss would swipe with her scythe. Roll through or away from the attack, then cast Crystal Soul Spear.

Defeat Nashandra and interact with the pillar of light. Two cutscenes would play. Skip both cutscenes and you would spawn at the Far Fire bonfire. Level up as appropriate and purchase all Brightbugs from Melentia, if any. It is time to prepare for the next NG cycle.