Howdy,
This guide will be teaching you how to kill K'ril Tsutsaroth (Zamorak) with ease. In order to kill K'ril Tsutsaroth, you will need a constitution level of 70.
K'ril Tsutsaroth can be killed with all combat styles, Ranged, Magic and Melee. Unfortunately, I won't go over every possible method such as using melee 2H to kill K'ril Tsutsaroth.

Note: It is entirely up to you whether or not you want to use prayer. If you're going to use prayer, do note that K'ril will perform a special attack, 15-25 seconds in, which will result in a considerable amount of damage dealt to you. However, you can easily heal yourself by killing the minions and/or eating.
K'ril Tsutsaroth's special attack is capable of dealing 6000 or more damage depending on damage reduction bonuses.

Ranged
Players are recommended to save up adrenaline for Death's Swiftness, otherwise kills will take too long and end up with shorter trips.

Item (most effective → least effective)
• Helmet; Slayer Helmet^{ON TASK} → Sirenic Mask  → (Superior)Death Lotus hood → Pernix Cowl → Armadyl Helmet.
• Body; Sirenic hauberk, Death Lotus chestplate → Pernix body → Armadyl chestplate.
• Bottoms; Sirenic chaps → Death Lotus chaps → Pernix chaps → Armadyl Chainskirt.
• Boots; Glaiven Boots → Pernix boots → Armadyl boots.
• Gloves; Ascension Grips → Tracking gloves → Swift gloves → Pernix gloves → Armadyl gloves.
• Amulet; Amulet of Souls → Farsight Sniper Necklace → Saradomin's murmur → (Blood) Amulet of fury.
• Cape: Completionist cape → Max cape → TokHaar-Kal-Xil → Skillcape
• Weapon; Noxious Longbow → Ascension Crossbows → Attuned Crystal Bow^{99 Agility} → Zaryte bow → Chaotic C'bows.
• Ring; Ring of death → Asylum Surgeons Ring → Sixth-Age Circuit → Ring of Wealth
• Aura; Penance → Reverence → Vampyrism

An example of a dual wield ranged ability bar:


Inventory - This is how you should want your inventory to look.
• Orange = Room for loot.
• Light blue = Replaceable with whatever potions you have available.
• Red = Spring cleaner - This is good for crushing any runite drops.

*A pack yak should be filled with the best food you have

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Melee

Item (most effective → least effective)
• Helmet: Slayer Helmet^{ON TASK} → Malevolent Helmet → (Superior)Tetsu Helmet → Torva Full Helmet → Bandos Helmet.
• Top: Malevolent → (Superior)Tetsu  platebody → Torva Platebody → Bandos Chestplate.
• Bottom: Malevolent → (Superior)Tetsu platelegs → Torva Platelegs → Bandos Tassets.
• Gloves: Pneumatic Gloves → Goliath gloves → Torva Gloves → Bandos Gloves.
• Boots: Steadfast boots → Torva Boots → Bandos Boots.
• Amulet: Amulet of Souls → (Blood)Brlawer's knockout necklace → (Blood)Amulet of fury → Saradomin's whisper.
• Cape: Completionist Cape → Max cape → TokHaar-Kal-Ket → Fire Cape.
• Weapon: Drygore Mace/Rapier/Longswords → Chaotic Longswords.
• Aura Penance → Reverence → Vampyrism.
• Ring: Ring of Death → Asylum's Surgeon Ring → Leviathan Ring → Ring of Wealth.

An example of a duel wield melee ability bar:


Inventory - This is how you should want your inventory to look.
• Orange = Room for loot.
• Light blue = Replaceable with whatever potions you have available.
• Red = Spring cleaner - This is good for crushing any runite drops.

*A pack yak should be filled with the best food you have

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Magic
Players are recommended to save up adrenaline for Sunshine, otherwise kills will take too long and end up with shorter trips.
Spells to use: Fire Surge > Fire Wave > Storm of Armadyl

Item (most effective → least effective)
• Helmet: Slayer Helmet^{ON TASK} → Tectonic Mask → (Superior)Seasigner Hood → Virtus Mask → Hood of Subjugation.
• Top: Tectonic Top → (Superior)Seasigner top → Virtus top → Garb of Subjugation.
• Bottom: Tectonic Bottoms → (Superior)Seasigner Bottoms → Virtus bottoms → Gown of Subjugation.
• Gloves: Celestial Handwarps → Static Gloves → Spellcaster Gloves → Virtus Gloves → Gloves of Subjugation.
• Boots: Ragefire Boots → Virtus Boots → Boots of Subjugation → Warpriest Boots.
• Amulet: Amulet of Souls → (Blood) Arcane Stream → Dragon-Rider Amulet → Saradomin's hiss → Blood Amulet of Fury.
• Cape: Completionist cape → Max cape → TokHaar-Kal-Mej → God Cape
• Weapon: Noxious Staff → Staff of Darkness → Attuned Crystal Staff → Chaotic Staff.
• Aura Penance → Reverence → Vampyrism.
• Ring: Ring of Death → Asylum's Surgeon Ring → Leviathan Ring → Ring of Wealth

An example of a 2H Magic ability bar:


Inventory - This is how you should want your inventory to look.
• Orange = Room for loot.
• Light blue = Replaceable with whatever potions you have available.
• Red = Spring cleaner - This is good for crushing any runite drops.

*A pack yak should be filled with the best food you have

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I hope that this guide helps and inspires you to take on bossing! If you'd like to see what items K'ril Tsutsaroth can drop, please click this link that will take you to the wiki. >K'ril TsutsarothDrops<
With help from the RS Wiki

You're the best Will upload this later tonight!

Also, if you time it right, you can use the Debilitate ability which will half the damage from K'rils spec

Thanks for the guide Damien!