Horror from the Deep

01Getting to the lighthouse

The lighthouse sits north of the Barbarian Outpost across a run of basalt platforms, and the platforms are the most dangerous part of the quest for a low-level account.

1. 1

   Travel to the lighthouse north of the Barbarian Outpost. Bring food — the platforms fail often even at reasonable Agility and hit hard when they do.

   The crossing can hit for 10. Arriving with no food is how people die on the way to a quest with no boss yet.

2. 2

   Pick up the two planks along the fence at the north-east end of the outpost on your way past, so you are not making the trip twice.

   • Plank
3. 3

   Speak to Larrissa outside. Her partner Jossik is inside the lighthouse, the light has gone out and the door is locked.

02The bridge and the key

1. 1

   Go east to the broken bridge. With a hammer and 60 steel nails, use a plank on your side, jump across, and use the second plank on the far side.

   • Plank
   • Hammer
   • Steel nails

   The bridge does not visibly change when it is fixed. Check the quest journal rather than trusting your eyes.

2. 2

   Head to the Barbarian Outpost and find Gunnjorn inside the Agility course, through the pipe. He hands over Larrissa's spare key.

3. 3

   Return to Larrissa and go inside. The room is wrecked, which is the quest telling you what is downstairs.

03Relighting it

1. 1

   Use molten glass and swamp tar on the light mechanism, then light it with a tinderbox.

   • Swamp tar
   • Tinderbox
2. 2

   Search the bookcase if you want the story. The diary is where the door downstairs is explained — the lock wants runes and weapons rather than a key.

3. 3

   Open the basement door using fire, air, water and earth runes, a sword or longsword you can afford to lose, and an arrow.

   • Air rune
   • Water rune
   • Earth rune

   The sword and the arrow are consumed. Do not use anything you would miss.

04The Dagannoth Mother

This is the fight the quest exists for, and it is a puzzle rather than a damage race. She changes form on a timer and each form is immune to everything except one attack type.

1. 1

   Bring all three styles: a melee weapon, a bow with arrows, and elemental spells covering air, water, earth and fire.

2. 2

   Watch her colour and switch to whatever she is currently vulnerable to. She cycles roughly every eighteen seconds, so there is time to change but not to hesitate.

   Hitting the wrong style does nothing at all. If your damage has stopped landing, she has changed form and you have not.

3. 3

   She resists melee heavily. Expect the magic and ranged phases to do most of the work.

4. 4

   Speak to Jossik afterwards and choose your reward. The Ancient, Armadyl and Bandos mjolnirs are cosmetic choices, but the god books are not — pick the one matching the god you will actually pray to.