Alchemical Hydra/Strategies Guide – OSRS

The Alchemical Hydra is a level 95 Slayer boss encountered in the Karuulm Slayer Dungeon. In order to fight it, players must be assigned a Hydra task.

To reach the boss, players must run north past the Tasakaal, then east past the Hydras. They will then reach the entrance to the lair by Orrvor quo Maten. Alternatively, players with level 88 Agility can reach it safely by using the mysterious pipe just behind Kaal-Ket-Jor.

Fight overview

The fight is instanced; if players die while fighting the Hydra, then they may reclaim their items from Orrvor quo Maten outside for 100,000 coins each time. Dying elsewhere with items still held by him will result in them being lost forever.

Note: While the Hydra is in the room, players cannot leave through the doors, as they are jammed when this occurs. Teleports will still work, however. The Hydra has a respawn time of 20 seconds.

The Hydra has four phases, each one beginning upon hitting or going past each 25% health threshold (~275 health). A head will fall off each time this occurs as the Hydra roars and changes forms, signifying the start of the next phase.

The Hydra attacks with both Magic and Ranged, with its left heads attacking with magic and its right with ranged. In the first two phases, this consists of two instant hits that deal less damage individually. Once one of the heads on the side fall off, this will turn into a single hit that can deal more damage. The Hydra will begin the fight with either combat style. For the first three phases, after every three basic auto-attacks, regardless of damage dealt, the Hydra will sway its heads backwards as a warning indicator that it is changing combat styles. Phase-specific special attacks do not count toward these three attacks. Players should be aware that the Hydra’s phase transition animation can override the attack swapping animation, so counting the attacks is still beneficial.

During the first three phases, the Hydra’s carapace is strengthened and will immensely reduce incoming damage by 75% of what it would have dealt. This must be removed by luring it to the appropriate chemical vent. The Hydra will Roaaaaaaaaaaar! via a message above its heads when it gets sprayed by the correct vent. If it gets sprayed by chemicals from an incorrect vent, its enrage stack will go up, increasing the damage of its attacks. At the start of each phase, the Hydra will perform three auto-attacks before performing a special attack.

Poison

In this phase, the Hydra starts with a green carapace, and should be lured to the red chemical pool. After the first kill, the player should stand right next to the red chemical vat (to the east) so that the Hydra is automatically lured to the red chemical pool as soon as it spawns.

After the first three attacks, the Hydra will launch 4 or 5 poison blobs around the player’s location; 1 on the player and 4 randomly around it. The blobs have a 3×3 splatter effect dealing up to 7 damage, and standing on the poison pools will deal up to 12 poison damage per tick. Both will cause a poison effect that deals 4 (indirect) or 6 (direct) damage; if players get poisoned, immediately clear its effects. The best way to avoid this attack is by standing west of the red chemical vat, all the way south, then move north two tiles when the Hydra is positioned over the chemical pool. When it spits poison, move west two tiles – this avoids the one targeting the player, and the other four will splatter east.

Once the Hydra reaches 75% of its health, the bottom-right head falls off and it changes its carapace to blue. The player should be running to the green vent after the poison attack.

Lightning

Now with a blue carapace, the Hydra should be lured to the green chemical pool.

Throughout the phase, the Hydra will launch an electric ball in the centre of the room, which spawns four lightning currents in the four corners of the chamber, although the order in which they appear in is random. The four pieces of lightning converge on the player’s location. Getting hit by them will bind the player and deal up to 22 damage.

Starting near the middle of the room and looping around one of the last lightning spawns, to escape the box they form, is the easiest way to avoid their damage. Players may also hug the northern wall and quickly move their way west while damaging the Hydra, which works especially well with any ranged weapon with a distance of 10. It is also possible to trap the lightning by standing in the north-west corner, moving one tile diagonally south-east when the lightning is two tiles away from you, and instantly moving one tile north. This does not despawn the lightning, so if the player were to move off of the tile, the lightning will start following them again.

Once the Hydra reaches 50% of its health, the bottom-left head falls off and it changes its carapace to red. Next, the player should run west to the blue vent if not already there from the lightning.

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

Flame

Now with a red carapace, the Hydra should be lured to the blue chemical pool.

Throughout the phase, the Hydra will occasionally walk to the centre of the chamber and face the direction the player is at. Once it reaches the centre, it will inflict a stun on the player, but they can still attack it. If the player is underneath the Hydra, then it forces them out into a random direction. Upon reaching the centre, it breathes 5×5 layer of fire to the player’s sides based on their location before staring down the middle and launching a tracking fire.

This tracking fire follows the player’s movement, and travels significantly faster the further the player is (or if they start running). Turning off run and walking in a line as the fire trails is the best course of action. Getting hit by any of the fires will result in the player taking up to 25 damage, followed by a subsequent bleed of 5 damage for 5 hits. The Hydra will not attack for roughly seven ticks after the tracking fire is launched.

Similarly to the lightning trap in the previous phase, the flames can be trapped in by standing on a specific tile adjacent to the green vents, seen in the demonstration to the right.

Once the Hydra reaches 25% of its health, the middle head falls off and it changes its carapace to grey.

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.

Enraged

Now with a grey carapace, the Hydra no longer needs to be lured to any chemical pools for this phase, as its damage reduction ability does not reset. During this phase, the Hydra’s attack speed will increase to every four ticks, and its enrage stack will increase to max, allowing it to deal up to 55 damage per hit.

The Hydra starts off this phase with the combat style opposite of what it used in the previous phase; if it attacked with magic, then it will start the phase with ranged. If the Hydra attacked with magic and changes to ranged as it transitions phases, it will still start with ranged attacks. Like Zulrah’s unusual green form near the end of its phases, the Hydra will alternate between both combat styles after every single auto-attack; there is no warning animation for this, unlike the previous three phases. Continue to switch prayers with each basic attack for the remainder of the fight. The player can safely 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 phase 1, and will continue to use it after every nine subsequent auto-attacks. The amount of poison spat generally depends if the fire attack is present on the field – if the side and tracking fires are both present, this will always result in one poison blob, whereas an empty field will usually result in five blobs. Be aware that the poison special attack does not count as a basic auto-attack; 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. Poison blobs will still deal damage, however.

Players may choose to bring a bracelet of slaughter to extend their slayer tasks, and sometimes bring it as a switch so that gloves with offensive stats can be worn for the majority of the kill. If going with this option, remember to switch to the bracelet sometime during this final phase. It can be convenient to switch to the bracelet while dodging the poison special, as prayer does not have to be changed during this attack, though optimally the offensive gloves should be worn as long as possible.

Equipment

Slot	Recommended equipment for Ranged – Item (most effective → least effective)
	Slayer helmet (i)	Black mask (i)	N/A	N/A	N/A
	Necklace of anguish	Dragonbone necklace	Amulet of fury	Amulet of glory	N/A
	Dizana’s quiver	Ava’s assembler	Max cape / Ranging cape(t)	Ava’s accumulator / Ranging cape	N/A
	Masori body (f)	Crystal body / Eclipse moon chestplate	Hueycoatl hide body	Blessed body	N/A
	Masori chaps (f)	Crystal legs / Eclipse moon tassets	Hueycoatl hide chaps	Blessed chaps	N/A
	Twisted bow	Toxic blowpipe[a] / Dragon hunter crossbow[b]	Bow of faerdhinen	Eclipse atlatl[c]	N/A
	Twisted buckler	Dragonfire ward	Odium ward	Book of law	N/A
	Dragon arrow (Twisted bow) / Ruby dragon bolts (e) (crossbow) / Atlatl darts (for Atlatl)	Ruby bolts (e) (crossbow)	Rada’s blessing 4 (blowpipe or bow of Faerdhinen)	Any god blessing / Rada’s blessing 3 (blowpipe or bow of Faerdhinen)	N/A
	Zaryte vambraces	Blessed bracers / Hueycoatl hide vambraces	Barrows gloves	Black d’hide vambraces	N/A
	Pegasian boots[d]	Devout boots[d]	Blessed boots[d] / Aranea boots[d]	Boots of brimstone	Boots of stone
	Lightbearer (with a Zaryte crossbow switch)	Venator ring	Ring of the gods (i)	Ring of suffering (i)	Archers ring (i)
	Zaryte crossbow (Ruby dragon bolts (e))	Tonalztics of ralos[e]	Toxic blowpipe	Dragon warhammer[e]	N/A

Prayer bonus is prioritised over ranged accuracy because of the boss’s relatively low defensive stats and the minimal damage taken when dealing with the mechanics correctly. Alternatively, players may use gear that maximizes ranged accuracy if they are confident with prayer flicking, as it greatly reduces the need for prayer potions. With sufficient experience, barely any damage should be taken most kills; the only unavoidable damage players may take is the first hit at the start of kill, and self-inflicted damage from Divine potions or the special attack of Ruby bolts (e).

Inventory

1000

5000

1000

1000

• About 4–20 prayer potions or super restores.
  • More prayer potions allows for longer trips at the cost of not being able to bank hydra bones; however, banking the bones will lower overall kill rates due to time spent running to and from a bank, and is not recommended without Rada’s blessing 4.
• About 4-10 food, preferrably Cooked moonlight antelope.
  • As the player becomes more proficient at fighting this boss, they should take very little damage per kill, so excess food can be replaced with more prayer potions if doing long trips.
• Antidote++ if not bringing cooked moonlight antelope.
• Divine ranging potion, ranging potion, or bastion potion (the latter is largely superfluous, as all damage taken in the fight can be mitigated with prayer and good positioning once the player is experienced enough)
• House tablets or rings of dueling to restore stats and bank
• Rada’s blessing 4 for fast teleport back, if using a twisted bow (can be equipped if using bow of Faerdhinen or toxic blowpipe)
• Zaryte crossbow with ruby dragon bolts (e) is best used for its special attack during the flame phase to maximise the chance of skipping its flame wall attack. Particularly powerful when combined with the Lightbearer.
• Toxic blowpipe for healing special attack if using a twisted bow or bow of faerdhinen
• Divine rune pouch with runes for High Level Alchemy and Teleport to house (or two open slots for rune drops if using tabs/ring of dueling)
• (Optional) Bracelet of slaughter to extend the task
• (Optional) Bonecrusher or bonecrusher necklace to auto-bury hydra bones. Bonecrusher necklace can also be equipped during boss death animation to restore an extra 8 prayer points per kill.
• (Optional) Noxious halberd can be used to cure poison as necessary at the cost of 50% special attack energy.

Slot	Recommended equipment for Melee – Item (most effective → least effective)
	Slayer helmet (i)	Black mask (i)	N/A	N/A	N/A
	Amulet of rancour	Amulet of torture	Amulet of blood fury	Amulet of fury	Amulet of glory
	Infernal cape	Fire cape	Ardougne cloak 4	N/A	N/A
	Torva platebody	Bandos chestplate (or: )	Inquisitor’s hauberk	Mixed hide top	Obsidian platebody
	Torva platelegs	Bandos tassets (or: )	Inquisitor’s plateskirt	Mixed hide legs	Obsidian platelegs
	Scythe of vitur[a] > Dragon hunter lance (on stab)	Osmumten’s fang[b] / Ghrazi rapier	Blade of saeldor / Inquisitor’s mace (on stab)	Abyssal dagger > Noxious halberd / Zamorakian hasta (on stab)	Dragon sword > Dual macuahuitl
	Avernic defender	Dragon defender	Rune defender	Adamant defender	Dragonfire shield
	Rada’s blessing 4	Any god blessing / Rada’s blessing 3	N/A	N/A	N/A
	Ferocious gloves	Barrows gloves	Dragon gloves	Regen bracelet	N/A
	Primordial boots [c]	Aranea boots [c] > Dragon boots[c] / Echo boots[c]	Granite boots	Devout boots[c]	Boots of brimstone
	Lightbearer / Ultor ring	Berserker ring (i)	Brimstone ring	Treasonous ring (i) > Ring of shadows	Ring of the gods (i)
	Bandos godsword[d] / Burning claws[e] (on stab)	Dragon claws	Voidwaker / Saradomin godsword[f]	Elder maul[d] > Dragon warhammer[d]	Dragon dagger / Abyssal dagger

• Strength bonus is preferred over prayer bonus for melee.
• Melee setups often provide similar damage output to range setups, especially when a good special attack weapon is available, and typically have lower to no upkeep cost for weapons and armour.
• When meleeing Hydra, effectively luring it over the vents without missing attacks can be more complex than using a range setup.
• Despite having low defence, the Hydra has enough health that a small improvement in DPS from defence reduction adds up greatly over the course of the fight.
• On average, unless the ultor ring adds a max hit of 5 to a dragon hunter lance, lightbearer and a strong spec weapon will result in faster kill times.
• Damaging special attacks should be used during the flame phase to maximise the chance of phasing him before the flame wall attacks, except for when using burning claws, as this phase specifically is immune to burn damage.
• Learning to skip the flame phase will significantly speed up kill times and reduce the chance to take damage during the phase.

Inventory (If banking bones)

1000

5000

• 1 Divine super combat potion or Super combat potion.
• 4-15 Prayer potions, find what works for you. Each kill should take around 1:45-2:15 with close to max gear and stats. Prayer flicking can help make the most out of the potions, allowing for more efficient trips.
• Special attack weapon, or multiple if using lightbearer. Any defence reduction special to use at the start of kills, and then spare special attack energy can be used with the DPS special.
• Fill your inventory with the rest high healing food, such as manta rays or cooked moonlight antelope. The latter negates the need for bringing antipoison, as it will cure poison after being eaten, and its healing delay should not be an issue for skilled players. As you gain more experience, less or no food is necessary.
• 1 antidote++ or sanfew serum if not bringing cooked moonlight antelope.
• Divine rune pouch with runes for High Level Alchemy and Teleport to house (or two open slots for rune drops)
• House tablets or other teleport of choice to restore stats and bank if using divine pouch space to pick up rune drops.
• (Optional) Bracelet of slaughter to extend the task
• (Optional) Noxious halberd can be used to cure poison as necessary at the cost of 50% special attack energy.

Inventory (Long trips)

	5000

5000

10000

5000

1000

• 2-3 Divine super combat potions or Super combat potions.
• Special attack weapon, or multiple if using lightbearer. Any defence reduction special to use at the start of kills, and then spare special attack energy can be used with a DPS and/or Sustain special attack as needed.
• Fill your inventory with super restores or prayer potions, 1-2 prayer regeneration potions, and 1-2 sanfew serums for poison immunity. If less experienced with the boss, bring a few pieces of high healing food such as manta ray or cooked moonlight antelope. As you gain more experience, less or no food is necessary, especially if bringing saradomin godsword or amulet of blood fury.
• Holy wrench or prayer cape/max cape to increase prayer restored from potions.
• 1 antidote++ if not bringing cooked moonlight antelope or sanfews.
• Divine rune pouch with runes for Resurrect Greater Ghost, Death charge, and optionally Sinister Offering for more Prayer experience.
• (Optional) Bracelet of slaughter to extend the task.
• (Optional) Bonecrusher necklace to auto-bury hydra bones if not using Sinister Offering. It can also be equipped during boss death animation to restore an extra 8 prayer points per kill. This will restore 2 more points of Prayer than offering, but for much less exp.
• (Optional) Noxious halberd can be used to cure poison as necessary at the cost of 50% special attack energy.