Thermonuclear Smoke Devil OSRS Guide: 93 Slayer & Strategy

Overview: Thermonuclear Smoke Devil at a Glance

The Thermonuclear Smoke Devil, or Thermy, is the boss version of smoke devils, found in the Smoke Devil Dungeon south of Castle Wars. You need 93 Slayer and a smoke devil task to attack it; the only off-task kill is the one for the elite Western Provinces Diary.

Its only attack is a magical ranged hit of up to 8 every 2 ticks, and it has 100% prayer penetration, so protection prayers do nothing. You handle it with healing (Redemption, brews or blood spells), by walking under it between your attacks, or by safespotting it from 9 tiles with magic. Wear a facemask, gas mask or Slayer helmet, because the dungeon smoke damages you and drains your stats without one.

Kill it with magic or melee and leave ranged at home: its ranged defence is +900. Its Magic level is only 1, which is why spells still land through its +800 magic bonus, and its melee bonuses are tiny, with slash lowest at +4.

Access Requirements

• 93 Slayer. Each kill is 240 Slayer XP.
• A smoke devil task from Konar, Nieve, Duradel or Mortimer.
• A facemask, gas mask or Slayer helmet for the dungeon.
• Off task, one kill is allowed for the elite Western Provinces Diary, and only with 93 Slayer unboosted. Stay in the room until the death animation ends or the diary task does not count.

The boss requirements checklist lists the other Slayer boss gates by group.

Location and How to Get There

Thermy sits in its own section of the Smoke Devil Dungeon, which is in Chompy Marsh south of Castle Wars.

Fairy ring BKP puts you just south-west of the entrance, so run north-east. Without fairy rings, teleport to Castle Wars with a ring of dueling and run south-west. Inside the dungeon, head north-west to the crevice that leads to the boss.

Recommended Combat Stats and Gear

• Magic: Tumeken's shadow at the top, then the Eye of Ayak, harmonised nightmare staff and Sanguinesti staff. Ancestral or virtus, an imbued god cape and an imbued heart for the Magic boost.
• Melee: Scythe of Vitur, Soulreaper axe, Osmumten's fang or abyssal tentacle, with dragon claws as the special attack.
• A ring of suffering (ri) deals more through recoil than a berserker ring (i) gives you in damage, unless you are using a scythe.

Inventory and Supplies

• Super restores or prayer potions. Prayer here is for Redemption and offensive prayers, never protection.
• Brews and dark crabs, or less food if you heal with Blood Barrage or a Sanguinesti staff.
• Divine super combat potions for melee, or a saturated heart for magic.
• Dragon claws if you are meleeing.
• A rune pouch and a house teleport tablet.

Mechanics: Attack Styles, Max Hits and Immunities

Where Thermonuclear Smoke Devil Sits in Progression

Thermonuclear Smoke Devil is the entry point for the Slayer boss group, so there is nothing easier here to warm up on. Above it sit Cerberus and Skotizo.

Fight Strategy: Three Ways to Handle an Unblockable Hit

Walk under it

Attack, then step under the boss straight away. It cannot hit you while you are underneath, so it gets about one attack per attack of yours instead of 2 to 2.5. The wiki puts that at 50 to 60% less damage taken. Clicking an item or object while underneath, such as the ashes it drops, stops it from moving.

Safespot it with magic

Your spells reach 9 tiles and its attack reaches 8. Freeze it, step back to the ninth tile and keep casting. Powered staves need the longrange style for this, the Eye of Ayak cannot safespot at all, and the ice ancient sceptre adds 1 to 3 freeze ticks.

Tank it with Redemption

With 49 Prayer, Redemption heals 25% of your Prayer level (24 HP at 96 or higher) when you drop below 10% of your max hitpoints. Its max hit is 8, so never sit below 9 hitpoints, and turn Redemption back on after every trigger.

Thermy walks through other monsters and players. You cannot use the smaller smoke devils in the lair to block it, and a scythe can clip a stray smoke devil that wanders under the boss.

Drops and What Thermonuclear Smoke Devil Is Worth

The uniques are the occult necklace, smoke battlestaff, dragon chainbody, Jar of Smoke and the Pet smoke devil. The occult needs 70 Magic and adds 5% magic damage; the smoke battlestaff gives unlimited air and fire runes plus 10% accuracy and damage on standard spellbook spells.

Hard clue scrolls are a regular drop, and elite clues are possible. Regular smoke devils also drop the occult necklace, so a smoke devil task gives you two tables to roll on.

Combat Achievements

Thermy has three Combat Achievement tasks, all elite and worth 4 points each.

The magic safespot is the natural route to Hazard Prevention: a boss held outside its 8-tile range cannot hit anyone.

Combat Achievements guide

Ironman Notes

Smoke devil tasks come from Konar, Nieve, Duradel and Mortimer, and each Thermy kill is 240 Slayer XP.

The occult necklace is the big ironman upgrade here, and the smoke battlestaff saves you air and fire runes for every standard spell you cast afterwards.

Common Mistakes and Death Causes

• Praying Protect from Missiles or Protect from Magic. Its attack ignores both.
• Entering without a facemask, gas mask or Slayer helmet.
• Bringing ranged into +900 ranged defence.
• Letting hitpoints drift below 9 on the Redemption method.
• Trying to block it with the smaller smoke devils. It walks through them.
• Leaving the room before the death animation ends on the diary kill.

FAQ

What do I need to fight the Thermonuclear Smoke Devil?

93 Slayer, a smoke devil task and a facemask, gas mask or Slayer helmet.

Which protection prayer should I use?

None. Its attack has 100% prayer penetration. Use Redemption, healing, the walk-under trick or a magic safespot instead.

How hard does it hit?

Up to 8, every 2 ticks. It has 240 hitpoints.

Can I kill Thermy without a Slayer task?

Once, for the elite Western Provinces Diary, with 93 Slayer unboosted. Every other kill needs a smoke devil task.

What is the best combat style for Thermy?

Magic or melee. Ranged runs into +900 ranged defence, while its Magic level of 1 and +4 slash defence make the other two styles work.

Can I fight Thermy with a friend?

Yes. Thermy and the Kraken are the only Slayer bosses you can fight alongside another player.

Where is the Thermonuclear Smoke Devil?

In the Smoke Devil Dungeon south of Castle Wars. Use fairy ring BKP or a ring of dueling to Castle Wars, then go north-west inside the dungeon to the crevice.

Is Thermy worth doing?

On a smoke devil task, yes. The occult necklace and smoke battlestaff are real upgrades for a magic account, and the kill is short once your healing method is set.

Related Guides

• Slayer Bosses Ranked By Difficulty And Profit
• Alchemical Hydra Guide Phases Gear Chemicals Drops
• PvM progression guide
• Best bosses for money
• Combat Achievements guide

Bottom Line

Thermy is a healing check. Its 8 max hit cannot be prayed, so choose one method (walk-under, magic safespot or Redemption) and build the inventory around it. Once that is settled, the kill is short and the occult necklace comes with volume.

If you want the occult without the task grind, our Thermonuclear Smoke Devil service is done by hand with no automation. Otherwise the bosses list has the full index.