Cave Horrors are a mid-level Slayer monster and the only source of the Black Mask in OSRS — the core component of the Slayer Helmet. They’re located in Mos Le’Harmless, an island requiring a specific quest to access. Once you’re set up, Cave Horrors are a straightforward Slayer task that rewards patience with one of the most valuable Slayer drops in the game.
- Located in Mos Le’Harmless Cave on Mos Le’Harmless island
- Requires completing Cabin Fever to access Mos Le’Harmless
- Minimum 58 Slayer to kill Cave Horrors
- A Witchwood Icon must be worn or carried — without it, Cave Horrors drain your Prayer
- Black Mask drops at 1/512 — the reason most players target this task
How to Get to Cave Horrors in OSRS
Cave Horrors are found inside the cave on the south side of Mos Le’Harmless. Reaching the island requires completing Cabin Fever, which grants access to the island’s port.
Travel options:
- Fairy Ring DLR — teleports directly to Mos Le’Harmless with no additional travel. Enter from the north side of the island, run south to the cave entrance. Requires partial Fairytale II and Cabin Fever for the island to be useful.
- Book of Char (unlocked in Cabin Fever) — port access from Port Phasmatys. Sail to Mos Le’Harmless.
- Charter Ship to Mos Le’Harmless — available from any charter port; costs a small GP fee.
- Ectophial to Port Phasmatys then Charter Ship — slightly slower than Fairy Ring but works pre-diary.
ℹ️ A Witchwood Icon must be equipped or in your inventory while fighting Cave Horrors. Without one, Cave Horrors drain your Prayer points progressively. Buy the icon from Jiminua’s Jungle Store on Mos Le’Harmless for 900 GP.
Cave Horror Combat and Slayer Tips
Cave Horrors are level 80 with 55 Hitpoints. They use melee attacks exclusively and have a moderate max hit of around 8–10. At 70+ Defence, most players tank them without prayer.
| Stat | Value |
|---|---|
| Slayer Level Required | 58 |
| Combat Level | 80 |
| Hitpoints | 55 |
| Max Hit | ~10 |
| Weakness | Crush |
Tips for efficient Cave Horror tasks:
- Use Guthan’s set or high-healing food if on a longer trip — their damage is low, but volume adds up
- Cannon placement works inside the Cave Horror area — significantly speeds up tasks
- The cave is multi-combat in sections; cannon coverage hits multiple enemies simultaneously
- Bring Witchwood Icon — the Prayer drain without it matters over longer tasks
The Black Mask Drop
The Black Mask drops at approximately 1/512 from Cave Horrors. Combined into the Slayer Helmet (via Malevolent Masquerade quest unlock and Slayer points), it gives a 15% accuracy and 15% damage boost against Slayer-assigned monsters. If you want to get to Cave Horrors without grinding Cabin Fever’s prerequisites first, our OSRS quest services handle the quest chain.
The Black Mask (i) imbued version (via Nightmare Zone) boosts Ranged and Magic damage on-task too — making the Slayer Helmet one of the most versatile helmets in the game for all combat styles during Slayer.
OSRS Cave Horrors FAQ
Below are the most common questions about reaching and farming Cave Horrors in OSRS.
What Quest Is Required for Cave Horrors?
Cabin Fever is required to access Mos Le’Harmless. It requires Pirate’s Treasure and Rum Deal as prerequisites. The full chain takes roughly 1–2 hours and grants access to one of the best Slayer task monsters in the mid-game.
Is the Black Mask Worth Farming at Cave Horrors?
The Black Mask is essential for the Slayer Helmet, which is best-in-slot for Slayer tasks. At 1/512, you might get it quickly or spend 2,000+ kills dry. Most players complete Cave Horror tasks during normal Slayer progression and eventually receive the mask naturally. Dedicated farming is viable for accounts that specifically need it.
Can You Use a Cannon at Cave Horrors?
Yes — Dwarf Multicannon works inside the Cave Horror area. Cannon dramatically speeds up tasks in the multi-combat sections. Bring cannonballs and place the cannon in a central spot for maximum coverage.
Do You Need the Witchwood Icon Every Visit?
Yes, every single visit. The Prayer drain effect is active any time a Cave Horror can reach you without the icon present. The drain rate is fast enough to empty your Prayer in minutes during active combat. The icon is cheap (900 GP) and lasts indefinitely — just keep it equipped.
How Many Cave Horror Kills for a Black Mask?
At 1/512 drop rate, the statistical average is 512 kills per mask. Many players receive it earlier; dry streaks beyond 1,500 kills aren’t unheard of. Since Cave Horror tasks are assigned in batches of 80–130 by most Slayer masters, you may need multiple task assignments before the mask drops.
Cave Horrors are one of those Slayer monsters that feel routine until the Black Mask drops — and when it does, it’s one of the most impactful single drops in mid-game OSRS.