Thermonuclear Smoke Devil OSRS Boss Guide
Slayer Bosses - Easy difficulty
Updated September 2026
Thermy is a level 93 Slayer boss in the Smoke Devil Dungeon, fought on a smoke devil task. It is the only source of the Smoke battlestaff and the Thermy pet, and it drops the Occult necklace at a better rate than normal smoke devils. The fight is mechanically simple and reaches 60-100 kills per hour, making it a strong low-effort Slayer moneymaker. This guide gives you a practical starting route, loadout direction, and decision-first checklist so you can get into consistent kills faster.
Quick Profile
AKA
Thermy
Requirements
93 Slayer
Suggested Style
Magic
Encounter Type
Slayer Boss
Boss Overview
Thermonuclear Smoke Devil is a slayer boss in theslayer bosses bracket. Slayer bosses reward route discipline across many task-driven runs.
The thermonuclear smoke devil attacks only with a typeless magical ranged attack that maxes just 8, so protection prayers do nothing against it. Its threat comes from high accuracy and a 2-tick attack speed, which adds up over a kill. The lair is also smoky, so you must wear a gas mask, facemask or Slayer helmet or take constant damage and stat drain.
For a first kill, a trident or powered staff plus a facemask is all you need. The main decision is whether to Blood Barrage for sustain or safe-spot it: its attack range is eight tiles while most spells reach nine, so freezing it and stepping back lets you attack without being hit. It can also be fought alongside another player, unlike most Slayer bosses.
Your current setup should match your trip objective. If you are learning mechanics, favor sustain and control. If you are already consistent, add damage gradually.
Optimize for sustainable task throughput with low error rates.
How The Fight Works
Entry Setup
Open each run with a consistent setup routine to reduce avoidable errors.
Core Mechanic Loop
Use the same clean mechanic cycle each kill for Thermonuclear Smoke Devil before adding optimizations.
Trip Sustain
Preserve supplies with low-risk choices so your average trip value stays stable.
Bank and Repeat
Reset quickly, review one improvement point, and keep run volume high.
Prep Checklist
- Lock one stable loadout before you chase max DPS variants.
- Pre-plan your inventory around your expected trip length.
- Set one clear objective for each trip (KC, task, uniques, or practice).
- Match setup choices to your Slayer task and trip goals.
Recommended Loadout
Safe spot north of boss. Cast from distance. Pet chance 1/3000.
Video Guides
Thermonuclear Smoke Devil Quick Guide
by QuickOSRS
Thermonuclear Smoke Devil Guide
by KhaiRs
Mechanic Checklist
Trip consistency and mechanic rhythm beat all-in DPS greed.
- Wear a gas mask, facemask or Slayer helmet in the lair or the smoke deals constant damage and drains your stats.
- Do not bother with protection prayers - Thermy's attack is typeless and prayer has no effect.
- To safe-spot it, freeze it with ice spells and step out of its 8-tile range while attacking from your spell's 9-tile range.
Common Mistakes
- Over-prioritizing damage upgrades before mastering mechanics.
- Bringing too many switches and losing consistency under pressure.
- Staying too long on weak supplies and losing overall hourly value.
Progression Targets
- Stage 1: Build a reliable Thermonuclear Smoke Devil starter setup in Gear Picker and secure consistent clears.
- Stage 2: Optimize trip length through cleaner mechanics and inventory control.
- Stage 3: Add a stronger DPS variant and compare real run outcomes.
- Stage 4: Finalize a shareable Thermonuclear Smoke Devil loadout set for your ongoing route.
Notable Drops
- Occult necklace
- Smoke battlestaff
- Pet smoke devil
Boss FAQ
01What setup style should I start with for Thermonuclear Smoke Devil?
Start with a Magic setup focused on consistency, then tune damage once your kill flow is stable. Build and test your own setup in the Gear Picker before long trips.
02Is Thermonuclear Smoke Devil good for profit?
Thermonuclear Smoke Devil can be strong for profit depending on your kill consistency, trip length, and unique drop luck. Prioritize repeatable clears over risky max-DPS setups.
03How should I use Gear Picker for Thermonuclear Smoke Devil?
Create one baseline loadout, one safer sustain loadout, and one upgraded version. Share each link so you can compare and discuss setups quickly.
04Should I use Best in Slot Finder or Gear Picker for Thermonuclear Smoke Devil?
Use Best in Slot Finder for recommendation-first starting points, then use Gear Picker to build and refine the exact setup you will actually run.
Sources & methodology
XP rates, requirements, and drop data in this guide are cross-checked against the OSRS Wiki and verified against in-game behaviour. Grand Exchange prices move daily, so treat GP/hr figures as estimates and confirm current prices with the OSRS Wiki price tracker before committing to a method.
Darren started playing the original RuneScape 2 back in the day and came back when Old School RuneScape launched. He's played on and off over the years and built OSRSToolkit to give players a single place to find reliable tools, calculators, and guides — all informed by real in-game experience.