Nebula Wiki

Introduction

Superior slayer monsters are more powerful monsters than their normal slayer monster. They can only be fought when you have the "Bigger Badder" slayer ability unlocked. Speak to any slayer master, and see their learn shop to purchase this ability.
A superior can only spawn on slayer task. They spawn upon defeating a slayer monster. However not all monsters have a superior version.
Like the Bigger Badder Ability, there's a similar ability for boss tasks called the "Superior Fury". Once learned, while on boss tasks bosses will be able to spawn their superior version. Speak to Hanto, the boss master at the Slayer camp.

Superior Rate Multipliers

There are ways to increase the chance for a superior to spawn. 
Here's all the available methods to increase your chance.
Superior Chance Increases
Where to obtain Location % Increase
Well of Goodwill West of Home 10%
Superior Wednesday None 15%
Bigger Badder 2 Ability Slayer Learn Shop 5% (Permanent)
Adventurer's Book Quest tab 1% (Permanent)

Boss Superior Rate Multipliers

You may increase the chance to spawn a boss superior through various methods. Here are all the current available methods
Boss Superior Chance Increase
Where to Obtain Location % Increase
Overdrive Ability Hanto's Learn Shop 5%

Superior Monsters

Here's a list of superior monsters, their rates and from which slayer master you can receive them.
List of Monster names, Spawn Rate and Slayer Master.
Monster Name Spawn Rate Slayer Master
Pyrefiend 1/250 Mazchna, Vannaka
Aberrant Spectre 1/250 Vannaka
Basilisk 1/250 Vannaka
Cave Horror 1/250 Vannaka
Jelly 1/250 Vannaka
Turoth 1/250 Vannaka
Bloodveld 1/250 Vannaka, Chaeldar
Jungle Horror 1/250 Vannaka, Chaeldar
Otherworldly Being 1/250 Vannaka, Chaeldar
Dust Devil 1/250 Vannaka, Chaeldar
Jungle Strykewyrm 1/250 Vannaka, Chaeldar
Infernal Spider 1/200 Vannaka, Chaeldar
Infernal Mage 1/250 Chaeldar
Nechryael 1/250, 1/150 Chaeldar, Sumona
Kurask 1/250, 1/150 Chaeldar, Sumona
Desert Strykewyrm 1/250, 1/150 Chaeldar, Sumona
Chilly Hand 1/250, 1/150 Chaeldar, Sumona
Dark Celestial 1/250, 1/150 Chaeldar, Sumona
Magma Elemental 1/250, 1/150 Chaeldar, Sumona
Magma Torcher 1/250, 1/150 Chaeldar, Sumona
Magma Beast 1/250, 1/150, 1/100 Chaeldar, Sumona, Kuradal
Lichwood Stag 1/250, 1/150, 1/100 Chaeldar, Sumona, Kuradal
Grovewarden Snake 1/250, 1/150, 1/100 Chaeldar, Sumona, Kuradal
Loreroot Fungal 1/250, 1/150, 1/100 Chaeldar, Sumona, Kuradal
Gargoyle 1/250, 1/150, 1/100 Chaeldar, Sumona, Kuradal
Abyssal Demon 1/150, 1/100 Sumona, Kuradal
Abyssal Horror 1/150, 1/100 Sumona, Kuradal
Ice Strykewyrm 1/150, 1/100 Sumona, Kuradal
Shadow Demon 1/150, 1/100 Sumona, Kuradal
Dravonic Demon 1/150, 1/100 Sumona, Kuradal
Dravonic Devil 1/150, 1/100 Sumona, Kuradal
Dravonic Hydra 1/150, 1/100 Sumona, Kuradal
Fire Dragon 1/150, 1/100 Sumona, Kuradal
Infernal Demon 1/150, 1/100 Sumona, Kuradal
Balrog 1/150, 1/100 Sumona, Kuradal
Dark Beast 1/100 Kuradal
Tormented Beast 1/100 Kuradal
Crystalite Gargoyle 1/100 Kuradal
Ebonchill Dragon 1/100 Kuradal
Ebonchill Starlight 1/100 Kuradal
Dark Matter Demon 1/100 Kuradal
Dark Matter Gorak 1/100 Kuradal

Boss Superiors

Here's a list of boss superiors that you may obtain as a task and their spawn rate. Boss tasks can only be received as a task from Hanto, the boss master.
List of Boss names and spawn rate
Boss Name Spawn Rate
General Graardor 1/100
Kree'Arra 1/100
K'ril Tsutsaroth 1/100
Commander Zilyana 1/100
King Black Dragon 1/100
Sunfreet 1/100
Corporeal Beast 1/100
Blink 1/100
Exorian Champion 1/100
Gano. Behemoth 1/100
Nomad 1/100
Glacor 1/100
King Black Scorpion 1/100
Tormented Demon 1/125
Tor. Bloodchiller 1/125
Tor. Warmonger 1/125
Earthbreaker 1/125
Celestial Hunllef 1/115
Magma Reaver 1/115
Vorago 1/100
Exorian Nightmare 1/100
Akdall the Forsaken 1/100
Gothmog 1/100
Dark Matter Vyrewatch 1/100