[OSRS] Alchemical Hydra Guide 2023

Alchemical Hydra Guide OSRS

The Alchemical Hydra is a fearsome boss in Old School RuneScape (OSRS) located in the Karuulm Slayer Dungeon. It requires a Slayer level of 95 to be assigned as a task. The Hydra has three different forms, each with its unique attack style, making the fight challenging and dynamic.

                                                                        Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.

During the fight, the Hydra will switch between its different forms, which are the regular Hydra, the red Hydra, and the blue Hydra. Each form has different attacks, and players must adapt their combat strategies accordingly. The Hydra is also known for its unique drop table, which includes valuable items such as the Hydra's claw and the Hydra leather.To defeat the Alchemical Hydra, players should utilize appropriate gear, prayer switches, and combat techniques to maximize their chances of success. It is recommended to have high combat stats and good knowledge of the boss mechanics before taking on this formidable foe.

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Karuulm Slayer Dungeon (Lower Level)





The Karuulm Slayer Dungeon is a dungeon found in the northwest portion of Zeah. The Dungeon requires Boots of Stone, Boots of Brimstone, or Boots of Granite to explore past the initial chamber without taking incredible amounts of damage (4 damage every 1/2 tick).

  • Rada’s Blessing 3 or higher will teleport you directly to the entrance
  • Fairy ring C-I-R teleports you below the mountain, run north to the entrance
  • Skills necklace teleport to Farming Guild then run south-west
  • Battlefront Teleport then run north-west

The location of Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.

To access the Alchemical Hydra boss, players need to head north past the Tasakaal creatures, then continue eastward past the hydras. This path leads to the entrance of the lair, guarded by Orrvor quo Maten. Another option is available for players with level 88 Agility, who can use the mysterious pipe located just behind Kaal-Ket-Jor to reach the boss safely. However, using the mysterious pipe takes approximately the same amount of time as running past the hydras. Choose the route that suits your agility level and preference to face the formidable Alchemical Hydra in its lair.

The location of Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.

Fight overview

While facing the Alchemical Hydra in its lair, players should be aware that they cannot leave through the doors once the battle begins, as they become jammed during the encounter. However, teleports can still be used as an escape method.

The boss fight with the Alchemical Hydra consists of four phases, each triggered based on its remaining health. Throughout the fight, the Hydra alternates between Ranged and Magic attacks, with a pattern of three attacks of each type in the first three phases. At the start of each phase, the Hydra gains a 75% damage reduction, which can be removed by luring it over a vent that releases chemical liquid. It is crucial to lure the Hydra over the correct vent, matching the combat triangle. For example, when the vent is green, using the red combat style will weaken the Hydra. Otherwise, if the wrong vent is used, the Hydra's damage increases by up to 50%.

Upon reaching 75%, 50%, and 25% of its health (825, 550, and 275 Hitpoints, respectively), the Hydra loses one of its heads and enters the next phase. The damage reduction is reactivated, and the player should lure the Hydra over the next corresponding vent. Each phase also introduces special attacks: poison pools when green and black, electricity when blue, and fire when red. These attacks can be avoided with careful positioning and movement.

During the final phase, the Hydra behaves similarly to the last stage of Zulrah's rotation, starting from the opposite combat style used in the previous phase (e.g., if the previous phase ended with ranged, it will use magic). Additionally, the Hydra's maximum hit slightly increases in the final phase.

Upon successfully defeating the Alchemical Hydra, it will respawn in approximately 25 seconds, ready to challenge other brave adventurers.


The battle with the Alchemical Hydra takes place in an instanced area. If players die during the fight, they can retrieve their items from Orrvor quo Maten outside the lair by paying 100,000 coins each time. However, if players die elsewhere while still possessing items held by Orrvor quo Maten, those items will be lost permanently.

It is important to note that once the Hydra is in the room, players cannot leave through the doors as they become jammed. However, teleports can still be used as an escape method. The Hydra respawns 20 seconds after being defeated.

The Hydra's fight is divided into four phases, triggered when its health reaches or surpasses each 25% health threshold (approximately 275 health). Each phase begins with a head falling off as the Hydra roars and changes forms.

During the battle, the Hydra attacks with both Magic and Ranged. The left heads attack with magic, while the right heads attack with ranged. In the first two phases, the Hydra delivers two instant hits that deal less damage individually. In the last two phases, it delivers one hit that does higher individual damage. The Hydra starts the fight with either combat style. After every three basic auto-attacks in the first three phases (excluding phase-specific special attacks), the Hydra sways its heads backward as a warning before changing combat styles. Players should keep track of the attacks, although the Hydra's phase transition animation may override the attack swapping animation.

In the first three phases, the Hydra's carapace is fortified, reducing incoming damage by 75%. Players must remove this damage reduction by luring the Hydra to the appropriate chemical vent. When the Hydra gets sprayed by the correct vent, it will Roaaaaaaaaaaar! to signify this. However, if it gets sprayed by chemicals from an incorrect vent, its enrage stack will increase, leading to higher damage in its attacks. At the beginning of each phase, the Hydra performs three auto-attacks before executing a special attack.


The Poison Phase of Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.During this phase, the Alchemical Hydra starts with a green carapace, and players should lure it to the red chemical pool. After the first kill, position yourself right next to the red chemical vat (to the west) so that the Hydra is automatically lured to the red chemical pool as soon as it respawns.

After the first three attacks, the Hydra will launch 4 or 5 poison blobs around the player's location, with one on the player and the others scattered randomly. These blobs have a 3x3 splatter effect that can deal up to 7 damage, and standing on the poison pools will cause up to 12 poison damage per tick. Both the blobs and poison will inflict a poison effect dealing 6 damage. If you get poisoned, quickly clear its effects. To avoid this attack, stand to the west of the red chemical vat, all the way to the south. Then, move two tiles north when the Hydra is positioned over the chemical pool. When it spits poison, move two tiles west to avoid the targeted blob, and the other four will splatter to the east.

Once the Hydra's health reaches 75%, the bottom-right head falls off, and it changes its carapace to blue. At this point, run north to the green vent to initiate the next phase.


The Lightning Phase of Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.Now with a blue carapace, the Hydra should be lured to the green chemical pool.

During this phase, the Alchemical Hydra will launch an electric ball in the center of the room, which spawns four lightning currents in the four corners of the chamber. The order in which they appear is random. These four pieces of lightning converge on the player's location and can deal up to 20 damage while binding the player.

To avoid taking damage from the lightning, one effective strategy is to start near the middle of the room and loop around one of the last lightning spawns to escape the box they form. Another method is to hug the northern wall and quickly move west while damaging the Hydra, especially using a ranged weapon with a distance of 10. An advanced technique involves trapping the lightning by standing in the north-west corner, moving one tile diagonally south-east when the lightning is two tiles away, and then instantly moving one tile north. This traps the lightning, preventing it from despawning. However, if the player moves off the tile, the lightning will start following them again.

Once the Hydra's health reaches 50%, the bottom-left head falls off, and it changes its carapace to red. At this point, the player should run west to the blue vent if they are not already there from avoiding the lightning attacks.

Note: If the Hydra transitions to the next phase while there is lightning on the field, they will dissipate immediately.


The Flame Phase of Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.Now with a red carapace, the Hydra should be lured to the blue chemical pool.

During this phase, the Alchemical Hydra will occasionally walk to the center of the chamber and face the direction of the player. Once it reaches the center, the player will be stunned, but they can still attack the Hydra. If the player is underneath the Hydra, they will be forced out into a random direction. Upon reaching the center, the Hydra will breathe a 5x5 layer of fire to the player's sides based on their location before launching a tracking fire down the middle. This tracking fire follows the player's movement and travels faster the further the player is from the initial location (or if they start running).

To avoid the fire attacks, it is best to turn off run and walk in a straight line as the fire trails. Getting hit by any of the flames will result in the player taking up to 20 damage, followed by a subsequent bleed of 5 damage for five hits. Moving onto another fire will reset the bleed. The fires can be skipped by carefully navigating around them, but it is recommended to do so only after the tracking fire stops. The Hydra will not attack until four seconds after the tracking fire is sent out.

Similar to the lightning trap in the previous phase, the flames can be trapped by standing right next to the Hydra while facing a corner so that it uses the corner variant. As soon as the fire is launched from the Hydra's mouth, the player should immediately run to the other tile at a corner. This will cause the flame, which would have tracked the player, to end up trapped on the first flame tile, preventing it from extending.

Once the Alchemical Hydra's health reaches 25%, the middle head falls off, and it changes its carapace to grey. At this point, the player should prepare for the final phase of the fight.

Note: If the Hydra transitions to the next phase while performing this attack, it ends abruptly. This also includes the tracking fire, but any fires started before the phase transition will still persist as usual. For the duration of the side fires, the Hydra also becomes a solid NPC, meaning that it is not possible to walk under it.


The Enraged Phase of Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.During the final phase with a grey carapace, the Alchemical Hydra no longer needs to be lured to any chemical pools, as its damage reduction ability remains active. However, its attack speed will increase to every four ticks, and its enrage stack will reach its maximum, allowing it to deal up to 55 damage per hit.

At the start of this phase, the Hydra will use the combat style opposite of what it used in the previous phase. For example, if it attacked with magic in the previous phase, it will start this phase with ranged attacks. From this point on, the Hydra will alternate between both combat styles after every single auto-attack, without any warning animation as seen in the previous phases. Players should continue switching prayers with each basic attack for the remainder of the fight. It is safe to switch to the next prayer as soon as the Hydra starts its attack animation for the current attack.

After the first three auto-attacks, the Hydra will use the poison attack from the first phase, and it will continue to do so after every nine subsequent auto-attacks. Players should be aware that the poison special attack does not count as a basic auto-attack, and the Hydra's next attack style will still be the opposite of the auto-attack it used before the poison special. If the Hydra is killed just as it sends an auto-attack, it will deal no damage, but the poison blobs will still deal damage.

Some players may choose to bring a bracelet of slaughter to extend their slayer tasks and use it as a switch so that gloves with offensive stats can be worn for most of the kill. If using this option, remember to switch to the bracelet at some point during this final phase. It can be convenient to switch to the bracelet while dodging the poison special, as prayer does not need to be changed during this attack. However, for optimal performance, try to wear offensive gloves for as long as possible during this phase.

Recommended Equipment (Ranged)

The recommended ranged equipment to fight the Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.

Recommended Equipment (Melee)

The recommended melee equipment to fight the Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.


The recommended inventory to fight the Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.


The unique drop table of the Alchemical Hydra, a level 95 Slayer Boss in Old School RuneScape.

In conclusion, the Alchemical Hydra is a formidable boss located in the Karuulm Slayer Dungeon. It presents a challenging and rewarding combat experience for skilled adventurers. To reach the Hydra, players must navigate through the dungeon, and those with level 88 Agility have the option to use the mysterious pipe for quicker access.

The fight against the Hydra consists of four phases, each triggered by reaching certain health thresholds. Players must adapt their strategies and switch prayers accordingly as the Hydra alternates between Ranged and Magic attacks. Properly utilizing the chemical vents is crucial for removing the Hydra's damage reduction, and players must be cautious of its special attacks, such as the poison blobs, lightning currents, and fire attacks.

Successfully defeating the Alchemical Hydra grants commendable rewards, including valuable drops, Slayer experience, and Hydra's claw, which can be combined with the Dragon Hunter Lance. The Hydra is a Slayer boss, making it an ideal target for players looking to complete Slayer tasks or seeking challenging combat encounters.

Overall, the Alchemical Hydra offers an engaging and dynamic boss fight in Old School RuneScape, rewarding players with both riches and a sense of accomplishment upon victory. As with any challenging encounter, practice and mastery of the mechanics are key to prevailing against this fearsome beast. Good luck, and may you conquer the Alchemical Hydra with valor and skill!