Quick guide for Horror from the Deep

The Old School RuneScape Wiki also has an article on: osrsw:Horror from the Deep/Quick guide

This quest has an in-depth guide here. It contains a more detailed description of dialogue, cutscenes, and storyline.

Overview

Start point	Speak with Larrissa, who is outside the Lighthouse, north of the Barbarian Outpost.
Member requirement	Members only
Official difficulty	Experienced
Official length	Medium
Requirements	Skill requirements are not boostable unless marked with a [B] for boostable. Quests: Horror from the Deep Bar Crawl (miniquest) 35 Agility Recommended: 43 Prayer Ability to defeat a level 100 and level 84 monster, the second one being tricky.
Items required	Items from the tool belt are not listed unless they do not work or are not automatically added. For fixing the bridge: 60 steel nails 2 normal planks (can be obtained during the quest, just north of the fenced-in area of the Barbarian Outpost) For fixing the lighthouse mechanism: Molten glass 1 swamp tar Tinderbox (tool belt does not work) For activating the wall: 1 Fire rune 1 Water rune 1 Earth rune 1 Air rune A sword of any type that you are willing to lose An arrow of any type (except ogre and training) you are willing to lose
Recommended	A melee weapon (ideally a slash weapon), a ranged weapon (ideally thrown weapons), and runes for all four elemental spells to switch amongst in combat Games necklace and quick teleport tabs are very helpful to reach the Lighthouse during the quest. Houses by Rellekka are also helpful transportation methods. Lighthouse Teleport for quick teleportation to Larrissa
Enemies to defeat	Level 84 Baby Dagannoth Level 100 Dagannoth mother

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Getting started

Items recommended: Lighthouse Teleport or games necklace

• Head to the lighthouse north of the Barbarian Outpost and talk to Larrissa. ( 1•1•1•✓•3)…

  1	With what?
  1	But how can I help?
  1	Okay, I'll help!
  ✓	[Accept Quest]
  3	I'll see what I can do

Preparations

Items needed: 60 steel nails, 2 planks, molten glass, swamp tar, tinderbox (tool belt does not work), 1 free inventory slot

• Go south to the Barbarian Outpost, pick up two planks north of the Agility course.
• Enter through the gate (Bar Crawl miniquest must be done), then go through the Obstacle pipe.
• Talk to Gunnjorn. ( 1)…

  1	Talk about Horror from the Deep.

  (Make sure to have 1 free inventory slot)
• Far east of Larissa, go to a broken bridge, just past the crystal tree.
• Fix the bridge from both sides (requires crossing it from both sides).
• Talk to Larrissa.
• Search the northern bookcase on the 1^st floor^[UK]2^nd floor^[US] of the lighthouse ( 4)…

  4	Take all three books

  .
• Read the manual and diary.
• Go to the 2^nd floor^[UK]3^rd floor^[US] and use molten glass, swamp tar, then a tinderbox on the lighting mechanism.
• Return to Larrissa (now inside the lighthouse, ground floor^[UK]1^st floor^[US]).

The battle

Items needed: fire rune, air rune, water rune, earth rune (a staff will not work for any of these), any smithable sword, an arrow, combat equipment

• Climb the iron ladder to go to the lighthouse basement.
• To open the strange wall, use a fire rune, air rune, water rune, earth rune, a sword, and an arrow on it.
• Open the eastern strange wall.
• Go down the ladder and talk to Jossik, kill the Dagannoth, talk to him again and then kill the Dagannoth mother when it appears.
  • Strategies can be found here.
  • The following table shows her weaknesses in different forms:

Colour	Attack Weakness
White	Air spells (Air Strike, Bolt, Blast, Wave, and Surge)
Blue	Water spells (Water Strike, Bolt, Blast, Wave, and Surge)
Brown	Earth spells (Earth Strike, Bolt, Blast, Wave, and Surge)
Red	Fire spells (Fire Strike, Bolt, Blast, Wave, and Surge)
Orange	Melee attacks (at least rune weapons are recommended)
Green	Ranged attacks or special attacks (at least adamant or rune crossbow recommended)

The God Books

• Go to the 1^st floor^[UK]2^nd floor^[US] of the lighthouse.
• Show the rusty casket to Jossik.
  • If you had a full inventory when defeating the Dagannoth mother, you will not receive a rusty casket. Instead, you must talk to Jossik, who will have picked it up for you.
• You may now choose a book affiliated with three gods: Saradomin's Book of Wisdom, Guthix's Book of Balance or Zamorak's Book of Chaos.
  • Be sure to choose the same book twice in a row when he asks if you are sure about your selection.
• Quest complete!

Rewards

• 2 quest points
• 4,662 experience
• 4,662 experience
• 4,662 experience
• A damaged god book of your choice
• Dagannoth Mother is unlocked in Dominion Tower
• Access to the lighthouse general store and the dagannoth caves underneath (There are level 77 and 78 dagannoths. The level 77's use an inaccurate ranged attack, while the level 78's use a much more effective melee attack)
• The ability to request Dagannoths as a slayer task if the Mask of the Dagannoth is owned
• 2 Treasure Hunter keys (Ironman accounts will not receive these)
  

Music unlocked

• Out of the Deep
• Lighthouse

Required for completing

Horror from the Deep is directly required for the following quests/miniquests:

• Blood Runs Deep
• Recipe for Disaster
• Recipe for Disaster: Defeating the Culinaromancer

It is therefore an indirect requirement for the following quests and miniquests:

• Aftermath (miniquest)
• Full completion of Azzanadra's Quest
• Full completion of Battle of the Monolith (miniquest)
• Children of Mah
• City of Senntisten
• Full completion of Curse of the Black Stone
• Desperate Measures
• Full completion of Desperate Times
• Dishonour among Thieves
• Extinction
• Eye of Het I (miniquest)
• Eye of Het II (miniquest)
• Fate of the Gods
• Full completion of Heart of Stone
• Full completion of Hero's Welcome
• Kindred Spirits
• Koschei's Troubles
• Mahjarrat Memories
• Full completion of Missing, Presumed Death
• Nomad's Elegy
• Once Upon a Time in Gielinor: Finale
• Full completion of Once Upon a Time in Gielinor: Fortunes
• One of a Kind
• Sins of the Father
• Sliske's Endgame
• Tales of Nomad
• The Light Within
• The Mighty Fall
• Twilight of the Gods