Skeleton Lords
The Old Iron King is the next mandatory boss to defeat in order to unlock the gates of the Shrine of Winter. The path to the Old Iron King is guarded by the Skeleton Lords, Covetous Demon, and Mytha in that order. Let's make our way to the Skeleton Lords.
Speedrun through Huntsman's Copse NG+7, Dark Souls 2 SotFS
Majula
Purchase all Alluring Skull x 10 from Sweet Shalquoir as these items will be useful during the fight against the Skeleton Lords. However, the sorcery Yearn is the preferred option.
Proceed to the Rotunda at Majula and interact with the contraption to reveal the passage to Huntsman's Copse. While waiting for the grate to fully open, take the time to unclutter your inventory such as discarding items you have collected but do not need. For example, you might want to discard the Southern Ritual Band+2 dropped by Najka if you already have a copy of the ring. Collect the Rouge Water x 1 from the corpse near the grate. Proceed along the cliff edge to find and light the Undead Refuge bonfire as required. The bonfire can be safely ignored. Another bonfire is up ahead.
Huntsman's Copse
Sprint past all enemies until you are in front of a building. Wait for a Rogue to drop down and defeat this enemy. Then head into the building, turn left, head for the wooden door, turn around, and run outside the building. A Rouge is ambushing you from behind the door. Wait for various enemies to come outside and dispatch of them. Head back into the building to defeat another Rogue. Carefully navigate to the ledge in front of a ladder, wait for a Rogue to jump attack you, and defeat the enemy. Descend the ladder or drop down to find the Bridge Approach bonfire. This is the last bonfire at which you should rest before fighting the Skeleton Lords. Attune any spells you require for the upcoming boss fight. Yearn is the most useful spell for the fight. Crystal Soul Spear is also useful.
Cross a stone bridge and look for a mound in the distance. Head into the mound and pull a lever to lower a bridge. Cast Yearn along the way to distract various enemies. The Stray Hound near the mound is not affected by Yearn; use Crystal Soul Spear to get rid of this enemy. While waiting for the bridge to be fully lowered, cast Yearn one or two more times. Cross the bridge, turn left, and be ready to cast Yearn to distract the Rogue at the far end of the upcoming bridge. Run as quickly as possible past this Rogue and another Rouge guarding a cliff. Two more Rouges are ambushing you up ahead. Cast Yearn to distract them while you run past. Turn left into a narrow passage leading to the area where Merciless Roenna invades you. Consume a Brightbug prior to exiting the narrow passage. Once Roenna invades, you would not be able to use a Brightbug. Do not engage Roenna. Run past her and roll through her attacks. Up ahead should be a Rouge standing on a platform. Wait for the Rouge to drop off the platform, then jump onto the platform. Enemies cannot reach you while you stand on the platform, but do be wary of sorcery projectiles from the nearby Hollow Mage (or Necromancer). Quickly make any last minute preparation for the upcoming boss fight, such as consuming an item or drink your Estus Flask. Then drop off the platform and head for the boss arena behind the waterfall.
Skeleton Lords
Sorcerer versus Skeleton Lords NG+7, Dark Souls 2 SotFS
This is a gank boss. Initially you would find three large skeletons in the arena. These enemies are not affected by Alluring Skull or Yearn. Dash straight for the large skeleton in the middle and defeat it as quickly as possible. Wait for the enemy to die and an explosion to occur, then cast Yearn at some place high up in the arena. The Bonewheel Skeleton x 2 that spawn from the explosion would be attracted by Yearn. Now quickly defeat one of the remaining two large skeletons and then the remaining large skeleton. Every five or so seconds, cast Yearn to distract any skeleton minions that spawn. Once you have defeated all three large skeletons, it is time to take care of the skeleton minions. Cast Yearn at some place high above the arena, preferably aiming for the ceiling. The skeleton minions would clump together underneath where Yearn appears, giving you an excellent opportunity to kill multiple enemies at once. Cast Crystal Soul Spear at the skeletons. Alternatively, one-hand a great sword and R1 at the gang of skeletons. Cast Yearn every now and then to keep the skeleton minions preoccupied.
Defeat the Skeleton Lords, exit the arena, and pull a lever. Wait for the bridge to be fully lowered. Use the waiting time to discard items you have collected and do not need. For example, upon defeat the Skeleton Lords would drop the Clear Bluestone Ring+2. Discard this ring if you already have a copy. Cross the bridge and look for a cave in which you can find the Poison Pool bonfire. Light and rest at the bonfire to remove the poison from wading through the poison pool. Alternatively, ignore this bonfire and proceed ahead to Harvest Valley.