OSRS Mortimer Slayer Master: tasks, modifiers, and how he compares

Requirements and how to reach Mortimer

Mortimer is located in Wyrmscraig Cavern on the island of Wyrmscraig. Access requires at least partial completion of the Fallen From Grace quest. The published requirements are 70 Slayer and 100 Combat, or any combat level with 99 Slayer (you must show him the Slayer cape). This dual-path design accommodates both combat-focused accounts and skiller accounts that have invested heavily in Slayer.

To reach Wyrmscraig, you need 62 Sailing and a raft or skiff. Once on the island, Mortimer is found in the cavern. Teleport options include the Necklace of Passage, Slayer ring, or Ardeaglais teleport scrolls for faster return trips after the initial journey.

• 70 Slayer + 100 Combat, or 99 Slayer with Slayer cape.
• Partial completion of Fallen From Grace quest required.
• Located in Wyrmscraig Cavern — reached via Sailing or teleports.

Task assignment: choices, superiors, and what makes him different

Mortimer's defining feature is that he only assigns tasks that have a superior monster variant. This makes him the go-to master for players farming superior drops like the Imbued Heart (1/128 from superiors) and the Eternal Gem. Every task he offers has the potential for a superior encounter, which is not the case with Duradel, Nieve, or other masters.

He offers a choice of tasks rather than assigning a single monster. Initially you choose from two options; after completing 50 tasks with him, this increases to three choices. This choice system significantly improves the quality of your Slayer experience, as you can select the task that best matches your gear, location, and profit goals.

Mortifier modifiers: customising your task rewards

As you progress through tasks with Mortimer, you unlock modifiers called Mortifiers that change how your tasks behave. These include increased Slayer XP per kill, increased clue scroll drop rates, increased superior creature unique drop rates, and adjusted task quantities. Each modifier changes the reward profile without changing the assigned monster.

This system lets you tailor your Slayer sessions to your current goal. If you are training Slayer XP, prioritise the XP modifier. If you are farming Imbued Hearts, prioritise the superior drop rate modifier. If you want clue scrolls for profit, prioritise the clue rate modifier. The ability to switch modifiers between tasks adds a strategic layer that no other Slayer Master offers.

Mortimer vs Duradel vs Nieve: which master should you use?

The key difference is purpose. Duradel offers the highest Slayer points per task and access to the widest range of standard monsters. Nieve provides a balanced mid-tier option with moderate requirements. Mortimer offers neither standard points nor standard tasks — he is purely a superior-farming and high-level-choice specialist.

Mortimer's skip cost is 100 Slayer points (vs. the usual 30), and blocking costs 120 points. He also offers fewer block slots. Tasks from Mortimer cannot be skipped by visiting Turael. These restrictions make his task commitment heavier than other masters, so accept tasks carefully and use the choice system to select assignments you can complete.

• Duradel: highest standard points, widest monster range. Best for general Slayer progression.
• Nieve: balanced mid-tier. Good for accounts building toward end-game Slayer.
• Mortimer: superior-only tasks, choice system, Mortifier modifiers. Best for Imbued Heart farming and customised rewards.
• Mortimer tasks cannot be Turael-skipped. Skip cost: 100 points. Block cost: 120 points.