Following the purchase of the Golden Compass and completion of the Necromancers Palace, the Golden Cloud MountainsSlayer Area will become accessible. This area is the penultimate Slayer Area in the Throne of the Herald Expansion. The three Monsters within this area (Torvair, Arctair, and Harkair) drop the highest level, most powerful weapons in the game, which are extremely helpful in completing both Millennium Gate and Throne of the Herald. These can be extremely long grinds due to the difficulty of the monsters, and require quite a bit of preparation. Each weapon requires 100 fragments, and the fragments have a 5% drop rate, equating to 2,000 kills on average before accounting for item doubling bonuses. The player will also need to collect an additional 10 of each fragment in order to purchase the Golden Shard, adding another 200 kills for a total of 2,200 average kills required.
Acquiring these shards while fighting each monster as a slayer task is recommended, as fighting these monsters on task will increase the damage the player deals due to various buffs. This will require Auto Slayer to be disabled, will encourage semi-frequent check-ins, and means the order in which the weapons are obtained is effectively random, unless the player performs a significant amount of task re-rolling. If the player should choose to re-roll many times to guarantee the order of these monsters, or simply chooses to fight these monsters off task instead, then the suggested order is as follows:
The order in which the weapons are obtained is not particularly important. However, Monsters within the Millennium Gate area drop Vorloran armour, which is a significant upgrade over other Equipment available to the player up until this point. It is therefore suggested that each of the Golden Cloud Mountains monsters is initially only fought until 10 of each shard is obtained, at which point the Golden Shard can be purchased from the Shop. From here, monsters within the Millennium Gate area can be fought until some of the Vorloran armour pieces are obtained, after which the player can return to Golden Cloud Mountains to complete the grind for the weapons.
Broadly, an efficient order for finishing Slayer would be as below. Guides explaining strategies for fighting Millennium Gate monsters can be found at Millennium Gate/Guide.
Some equipment suggestions are detailed below. Note that depending on what Prayer, Potions, and Agility buffs the player uses or has access to, the optimal equipment may vary somewhat from these suggestions.
Buffs
Requirements
There are very few hard requirements beyond the entry requirement of Slayer Level 116 and completion of the Necromancers Palace, but there are several skills and items that will make this grind significantly easier, and it would be remiss to not mention them.
For Melee, use Battleborn and Valor or the highest level combat style prayers you have available.
For Ranged, use Battleborn and Avidity or the highest level combat style prayers you have available.
For Magic, use Battleborn and Divination or the highest level combat style prayers you have available.
In some situations, Holy Aegis may be required in order to achieve the required amount of Damage Reduction to safely idle a monster. Where relevant, this is mentioned below as part of the equipment recommendations.
For all combat styles, use Spectre and Occultist unless stated otherwise below. By decreasing the enemy's Evasion Rating, this Synergy significantly increases the player's chance to hit, even with otherwise maxed stats, and helps a lot in landing hits.
Alternatively, use Fox and Dragon to deal a significant amount of unavoidable damage when the player is otherwise having trouble hitting the target.
For all equipment suggestions, Consumable items such as the Explorers Map II are suggested, but are by no means required in order to safely idle these monsters. Therefore, this slot can be swapped for any other consumable item, or no consumable at all. The Slayer Deterer From Township can help reach the tight DR thresholds required provided the monster is only fought while on a slayer task.
Notes
Checking your setups with the Combat Simulator before engaging any of these monsters is highly recommended. Despite best efforts to ensure these equipment recommendations are safe, there is no guarantee that they will be safe in your specific circumstances.
While the Slayer Area Effect of Golden Cloud Mountains provides a large amount of Lifesteal, each monster ALSO has a passive ability that grants them +500% Lifesteal from Bleed. This makes Area Effect Negation not particularly effective, coupled with the fact that wearing Slayer armor can also prove detrimental to the player's Damage Reduction, it is best to not worry about the regular lifesteal, and focus on reducing the amount of ticks of Bleed the player takes.
As a result, Bleed Burner Cape is critically important for defeating these enemies efficiently. Possibly due to a bug, the way this cape's effect works causes each tick of bleed (there are 20 over the duration of a typical bleed) to each have a chance of completely removing the effect. For example, while the Bleed Burner Cape gives the player a 50% chance to completely ignore the bleed before it is applied, it is also possible for the bleed to suddenly expire after only dealing 1 or 2 ticks of damage, massively reducing the damage the player takes, and therefore the Lifesteal the enemy receives.
To be able to safely idle Torvair with Magic, the following build assumes the player has at least 1,200 HP and 98% out of combat DR (76% in combat). This equipment recommendation is suitable for all official Game Modes.
The Witch + YakSynergy and Holy Aegis are required to meet this damage reduction threshold. Note that this equipment leaves a very thin margin of safety, and therefore any deviation from the recommendation which reduces the player's damage reduction is not advised.
To be able to safely idle Torvair with Magic, the following build assumes the player has at least 1,200 HP and 100% out of combat DR (76% in combat). This equipment recommendation is suitable for all official Game Modes.
Acquiring some pieces of the armour dropped by the Vorloran Devastator provides some much needed Damage Reduction increases, allowing for more DPS-focused choices to be made. Using the Slicing Maelstrom Wand provides a very significant improvement to the kill rate, so is highly recommended.
As before, the margin of safety is very small, therefore if not using the full set of Vorloran Devastator armour then using Holy Aegis in place of Divination is suggested to maintain a safe level of DR. At least three pieces of Vorloran armour are recommended.
To be able to safely idle Arctair with Melee, the following build assumes the player has at least 1,200 HP and 100% out of combat DR (82% in combat). This equipment recommendation is suitable for all official Game Modes.
The Minotaur + YakSynergy and Holy Aegis are required to meet this damage reduction threshold. Note that this equipment leaves a very thin margin of safety, and therefore any deviation from the recommendation which reduces the player's damage reduction is not advised.
Spectral Ice Sword can be used instead of FrostSpark 1H Sword if necessary, however doing so is a significant increase in kill times, taking approximately 33% longer on average per kill.
To be able to safely idle Arctair with Melee, the following build assumes the player has at least 1,200 HP and 101% out of combat DR (82% in combat). This equipment recommendation is suitable for all official Game Modes.
To be able to safely idle Harkair with Ranged, the following build assumes the player has at least 1,200 HP and 83% out of combat DR (55% in combat). This equipment recommendation is suitable for all official Game Modes.
To be able to safely idle Harkair with Ranged, the following build assumes the player has at least 1,200 HP and 90% out of combat DR (63% in combat). This equipment recommendation is suitable for all official Game Modes.
Vorloran Watcher armour is not so important here, as the Damage Reduction requirement can be met without it with a negligible impact on kill rate. Further, if using Vorloran armour then only equip the Platebody, Gauntlets, and Boots, as the Mask of Torment and Perfect Sight Legs improves the kill rate when compared to the equivalent Vorloran Watcher equipment pieces.
Golden Compass and completion of the 
Necromancers Palace, the 
Golden Cloud Mountains Slayer Area will become accessible. This area is the penultimate 
Slayer Area in the 
Throne of the Herald Expansion. The three Monsters within this area (
Torvair, 
Arctair, and 
Harkair) drop the highest level, most powerful weapons in the game, which are extremely helpful in completing both 
Millennium Gate and 
Throne of the Herald. These can be extremely long grinds due to the difficulty of the monsters, and require quite a bit of preparation. Each weapon requires 100 fragments, and the fragments have a 5% drop rate, equating to 2,000 kills on average before accounting for item doubling bonuses. The player will also need to collect an additional 10 of each fragment in order to purchase the 
Golden Shard, adding another 200 kills for a total of 2,200 average kills required.
Auto Slayer to be disabled, will encourage semi-frequent check-ins, and means the order in which the weapons are obtained is effectively random, unless the player performs a significant amount of task re-rolling. If the player should choose to re-roll many times to guarantee the order of these monsters, or simply chooses to fight these monsters off task instead, then the suggested order is as follows:
Agile Wings Rapier shards
Slicing Maelstrom Wand shards
Feather Storm Crossbow shards
Vorloran Devastator, until at least 3 different Vorloran Devastator armour pieces have been obtained
Vorloran Watcher, until at least 3 different Vorloran Watcher armour pieces have been obtained
Vorloran Protector, until at least 3 different Vorloran Protector armour pieces have been obtained
Slayer Gear Upgrade Kit (Mythical). An added benefit is the increased damage given by buffs like the 
Slayer Skillcape and 
Astrology while fighting Slayer Tasks. Another benefit is the ability to buy 
Prayer Points, 
Light Runes, and Food at a profit with the use of 
Bountiful Resupply.
Potions, and 
Agility buffs the player uses or has access to, the optimal equipment may vary somewhat from these suggestions.
Level 120
Level 115
Spectre and 
Fox Synergies
Battleborn
Vorloran Protector Armour
Melee armour.
Vorloran Watcher Armour
Ranged armour.
Vorloran Devastator Armour
Magic armour.
Diamond Luck Potion, which frees up a potion slot for 
Damage Reduction Potion IV. It is necessary to have this obstacle at 99 
Mastery to halve the -100 HP modifier.
Valor or the highest level combat style prayers you have available.
Avidity or the highest level combat style prayers you have available.
Divination or the highest level combat style prayers you have available.
Holy Aegis may be required in order to achieve the required amount of Damage Reduction to safely idle a monster. Where relevant, this is mentioned below as part of the equipment recommendations.
Penetration Potion or 
Ranged Strength Potion may be used instead in order to improve the kill rate.
Occultist unless stated otherwise below. By decreasing the enemy's Evasion Rating, this Synergy significantly increases the player's chance to hit, even with otherwise maxed stats, and helps a lot in landing hits.
Dragon to deal a significant amount of unavoidable damage when the player is otherwise having trouble hitting the target.
Finn, the Cat, 
Leonardo, and 
Erran.
Explorers Map II are suggested, but are by no means required in order to safely idle these monsters. Therefore, this slot can be swapped for any other consumable item, or no consumable at all. The 
Slayer Deterer From 
Township can help reach the tight DR thresholds required provided the monster is only fought while on a slayer task.
Bleed Burner Cape is critically important for defeating these enemies efficiently. Possibly due to a bug, the way this cape's effect works causes each tick of bleed (there are 20 over the duration of a typical bleed) to each have a chance of completely removing the effect. For example, while the 
Agile Wings Rapier Shard used to create the 
Slicing Maelstrom, 
Despair, and 
Surge II.
Calamity Wand or 
Archaic Wand, use 
Infernal Power, 
Witch + 
Yak Synergy and 
Bundled Protection Body can be used in a pinch if either 
Freezing Touch Body or 
Slayer Wizard Robes (Mythical) are not available, however doing so is a significant decrease to the kill rate so is not suggested unless absolutely necessary.
Feather Storm Crossbow Shard used to create the 
Minotaur + 
Spectral Ice Sword can be used instead of 
FrostSpark 1H Sword if necessary, however doing so is a significant increase in kill times, taking approximately 33% longer on average per kill.
Vorloran Protector Platelegs, 
Vorloran Protector Boots, and 
Vorloran Protector Gauntlets equipped simultaneously is recommended. Alternatively, Vorloran pieces for 
Slicing Maelstrom Wand Shard used to create the 
Zephyte Bolts or 
Decay Bolts.
Divine Crossbow, use 
Meteorite Bolts.
Platebody, 
Gauntlets, and 
Boots, as the 
Mask of Torment and 
Perfect Sight Legs improves the kill rate when compared to the equivalent Vorloran Watcher equipment pieces.
Combat:
