Dragonrider x 2
You should have already defeated the four Old Ones: The Lost Sinner, The Rotten, The Duke's Dear Freja, and Old Iron King. You now have access to the Shrine of Winter and consequently Drangleic Castle, where the last boss of the game is located. The arena to the final boss is locked and is opened by the King's Ring. The ring is guarded by Velstadt, the Royal Aegis. Journey through Drangleic Castle, down to the Shrine of Amana, and across the Undead Crypt to find Velstadt.
Speedrun through Drangleic Castle NG+7, Dark Souls 2 SotFS
Shrine of Winter
Start from the Ruined Fork Road bonfire. Three paths are spread out ahead of you. The left-most path leads to Drangleic Castle, the middle path to Aldia's Keep, and the right-most path to Brightstone Cove Tseldora. Take the left-most path to Drangleic Castle. Have Alluring Skull (or Yearn) ready to distract two enemies along the way: a Goblin and a red phantom Goblin. Aim an Alluring Skull near the crumbled ruins. The Goblins would be distracted by the shattered Alluring Skull, but would not run towards it. You want the Goblins to stay at their spawn points because this would hinder or slow down any enemies that chase after you. Squeeze past the Goblins, run to the gate of the Shrine of Winter, and wait a while for the gate to open. Be careful of enemies who chase after you. Pass through the Shrine of Winter and descend a hill. The path ahead has two corpses: the first contains a Divine Blessing, the second a Human Effigy. Collect these as required.
Drangleic Castle
Proceed through a tunnel to reach the entrance to Drangleic Castle. Primal Knight x 2 stand mid-way along the staircase to guard the entrance. Dispatch of these enemies to clear a safe path ahead. Ascend to the top of the staircase and wait for a red phantom to approach you. Fight the red phantom one-on-one, away from the crossbow-wielding Royal Swordsman x 2. The gate of Drangleic Castle is guarded by Royal Swordsman x 2, each wielding a crossbow and stands near a stone golem. Defeat each enemy near a stone golem so that the soul of the enemy would be absorbed by the golem, hence activating it to open the gate. Royal Guard x 3 are masquerading as statues in the two rows of statues. Use these enemies as necessary to help you activate one or more stone golems. The longer you take to open the gate, the more Royal Swordsmen would spawn from behind a corner to fight you. After the gate is opened, you should be able to see the apparition of Chancellor Wellager standing at the top of a staircase. Purchase anything you need from him. In particular, you might want to stock up on Old Radiant Lifegem, Wilted Dusk Herb, and Repair Powder. Find and light the King's Gate bonfire. You will need this bonfire to access the final boss. Rest at the bonfire and attune any spells you require for the upcoming boss fight. In particular, you might want to attune Crystal Soul Spear or Sunlight Blade.
An adjacent room has rows of stone statues. You want to open the first stone gate to your right. Opening the gate requires the same logic as how you opened the gate to Drangleic Castle. Approach the gate to trigger Stone Soldier x 2 to re-animate and fight you. Defeat one Stone Soldier near the gate so its soul would be absorbed by the gate. Proceed through the gate, up some flight of stairs, and find the Forgotten Chamber bonfire. This bonfire is hidden behind an illusory wall. Light and rest at the bonfire if you want, or ignore the bonfire entirely and sprint straight to the boss fog wall.
Dragonrider x 2
Sorcerer versus Dragonrider x 2 NG+7, Dark Souls 2 SotFS
A copy-and-paste boss from Heide's Tower of Flame. However, you must now fight two at the same time. Upon entering the arena, you would find an archer Dragonrider standing on a platform to your left and a halberd-wielding Dragonrider straight ahead. Defeat the archer as quickly as possible because he has the least amount of HP. As soon as you enter the arena, lock onto the archer and perform four casts of Crystal Soul Spear to get rid of him. You should have already consumed a Brightbug prior to entering the fog wall, otherwise five casts of Crystal Soul Spear would be required to defeat the Dragonrider archer. Then be ready to fight the halberd-wielding Dragonrider who is running at you. Consider summoning Pilgrim Bellclaire to help take the pressure off you.
Defeat the Dragonrider x 2 and light the Central Castle Drangleic bonfire.