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Old School RuneScape (OSRS) offers a plethora of challenging bosses for adventurers to conquer, each with its unique mechanics and rewards. One such formidable foe is the Hydra, a multi-phase monstrosity residing within the Karuulm Slayer Dungeon. If you're seeking to test your mettle and reap valuable rewards, this guide will walk you through everything you need to know to defeat the Hydra boss in OSRS.

Hydra Boss Overview

The Alchemical Hydra, commonly referred to as just "Hydra," is a level 426 boss that can be assigned as a Slayer task. It resides in the Karuulm Slayer Dungeon, which requires level 75 Slayer to access. The Hydra is known for its three unique phases, each requiring different strategies and tactics to defeat. It drops valuable items, including the coveted Hydra leather and bones, which can be used to create the best-in-slot defensive gear.


Before you challenge the Hydra, make sure you meet the following requirements:

  1. Level 75 Slayer to access the Karuulm Slayer Dungeon.
  2. A Slayer task for Hydras assigned by Konar, Duradel, or Nieve.
  3. Decent combat stats: 90+ Attack, Strength, and Ranged are recommended.
  4. Prerequisite quests: The quest "Bone Voyage" is required to unlock access to Fossil Island, where you can build a Slayer ring for quick transportation to the Karuulm Slayer Dungeon.
  5. Suggested gear: High-quality melee, ranged, or magic equipment depending on your preferred combat style.

Hydra Boss Mechanics

The Hydra boss fight consists of three phases, each with its unique attacks and mechanics:

  1. Poisonous Phase: In this phase, the Hydra primarily uses Ranged attacks. It also occasionally sprays poison pools on the ground, which you should avoid standing in. When the Hydra's health reaches 75%, it transitions to the next phase.

  2. Electric Phase: During this phase, the Hydra uses both Ranged and Magic attacks. It will spawn three lightning orbs that must be destroyed to prevent it from healing. When the Hydra's health reaches 50%, it moves on to the final phase.

  3. Fire Phase: In the last phase, the Hydra exclusively uses Magic attacks. It will occasionally summon a wall of fire that moves towards you; you must dodge these while maintaining your DPS. Once the Hydra's health drops to 25%, it will be defeated.

Recommended Gear and Inventory Setup

Your gear and inventory setup may vary depending on your combat style. However, some general recommendations include:

Melee Setup:

  • Full Verac's or Karil's (for their prayer bonuses)
  • Prayer-boosting items like Ardougne Cloak or God Books
  • Barrows Gloves
  • Berserker Ring (i)
  • Dragon Hunter Lance
  • Super Combat Potions
  • Prayer Potions
  • Food (Sharks or better)
  • Extended Antifire Potion

Ranged Setup:

  • Elite Void Knight equipment (with Ranged helmet)
  • Amulet of Fury or Necklace of Anguish
  • Ava's Assembler (from the "Dragon Slayer II" quest)
  • Blowpipe with Addy or Rune darts
  • Rune Crossbow with Dragonfire Bolts (for the Electric Phase)
  • Ranging Potions
  • Prayer Potions
  • Food
  • Extended Antifire Potion

Magic Setup:

  • Ahrim's or Ancestral robes
  • Occult Necklace
  • Mage Arena 2 Cape (imbued for prayer bonus)
  • Trident of the Swamp
  • Kodai Wand (for the Electric Phase)
  • Prayer Potions
  • Food
  • Extended Antifire Potion

Ensure your inventory includes adequate food, potions, and prayer-restoring items. Use your preferred special attack weapon if you have one, such as the Dragon Warhammer for melee or the Dragon Crossbow for ranged.

Strategy for Defeating the Hydra

  1. Prayer Flicking: Prayer is essential to survive the Hydra's attacks. You'll want to use Protect from Missiles during the Poisonous Phase, Protect from Magic during the Electric Phase, and Protect from Missiles again during the Fire Phase. Practice prayer flicking to conserve prayer points and extend your trips.

  2. Dodge Special Attacks: Be aware of the Hydra's special attacks during each phase and react accordingly. Avoid standing in poison pools, destroy lightning orbs in the Electric Phase, and sidestep the moving wall of fire in the Fire Phase.

  3. Maintain DPS: To defeat the Hydra efficiently, focus on dealing consistent damage. Use your preferred combat style and special attacks wisely. Keep in mind that the Hydra has high Defense, so accurate and powerful attacks are crucial.

  4. Healing Mechanic: The Hydra has a healing mechanic in the Electric Phase. If you fail to destroy the three lightning orbs quickly, it will heal for a significant amount. Prioritize destroying these orbs as soon as they appear.

  5. Restocking Trips: Use your Slayer Ring or a House Teleport to replenish your supplies and prayer points between trips. Efficient trips are key to maximizing your kills per hour.

  6. Hydra Tail: The Hydra can drop the Hydra Tail, which can be used to create the powerful Bonecrusher necklace. If you receive one, it's recommended to keep it in your inventory or equipped, as it will automatically bury bones for Prayer experience.

Hydra Drops and Rewards

Defeating the Hydra in OSRS is a rewarding endeavor. Some of the notable drops include:

  • Hydra Leather: Used to craft Hydra Slayer gear, which provides the best defensive bonuses against magic and ranged attacks.
  • Hydra Bones: These can be used with a dragon bone at the Chaos Temple altar to create the Prayer-boosting bone, Ensouled Hydra Head.
  • Hydra Claw: A rare drop that can be combined with a Zamorakian hasta to create the powerful Dragon Hunter Lance.
  • Hydra's Eye, Fang, and Heart: Used to upgrade the Brimstone Ring, creating the Ring of Suffering, which offers valuable defensive bonuses and damage absorption.
  • Alchemical Hydra Heads: These can be used to recolor the Slayer helm to the Hydraken color.


Defeating the Hydra boss in OSRS is a challenging but rewarding experience. With the right gear, strategy, and preparation, you can conquer this multi-phase monster and earn valuable drops. Whether you prefer melee, ranged, or magic combat, the Hydra offers a unique

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