Thermonuclear Smoke Devil Best in Slot Gear & Strategy Guide

The non-negotiable requirement is 93 Slayer — without it you simply cannot damage thermy, and stat-boosting your Slayer to 93 does not work here (the game blocks boosted kills). You also must be on an active smoke devil Slayer task assigned by Konar quo Maten, Nieve, or Duradel to attack the boss at all. The lone exception is a single kill toward the Western Provinces Diary, which still demands a genuine, unboosted 93 Slayer.

Thermy lives in a separated chamber of the Smoke Devil Dungeon, south of Castle Wars. The fastest route is the fairy ring code BKP, which drops you just outside, then run to the dungeon entrance. If you have not unlocked fairy rings, teleport to Castle Wars (a ring of dueling is ideal) and run south-west to the dungeon entrance. Once inside, head to the crevice that leads into the boss's section.

Two quirks shape every trip. First, thermy is one of the very few Slayer bosses (alongside Kraken) that can be fought with another player in the room, and it can walk through other monsters and players — this is deliberate, to stop you safespotting it behind the smaller smoke devils in its lair. Second, a dwarf multicannon will be destroyed if you try to set one up in the boss room, just like at the King Black Dragon and Kalphite Queen, so leave the cannon at home.

Magic is the meta style here, and for a clear reason: thermy attacks as a 'magical ranged' boss, meaning its accuracy is checked against your magic defence — so stacking magic gear both raises your damage and makes you tankier at the same time. There is no wasted stat: the same robes that boost your spells also reduce how often the boss lands a hit. The boss also has a 20% elemental weakness to Air (wind) spells, added in the 25 June 2025 'Summer Sweep Up: Combat' update, which rewards air-spell setups built around staves like the harmonised nightmare staff or a Kodai wand on air spells. A Magic level of 75 or higher is advised so you can equip the strongest staves.

The fastest kills come from high-end powered staves — the wiki lists Tumeken's shadow at the top, with the eye of ayak, harmonised nightmare staff (on air spells), and the Sanguinesti staff or trident of the swamp below it. Pair that with the standard mage power families: occult necklace, an imbued god cape (or an Ardougne cloak), top-tier robes such as ancestral, virtus, or Ahrim's, a magic-defence shield like Elidinis' ward (f) or an arcane spirit shield, and a Magus or ring of suffering. An imbued or saturated heart is worth bringing because the higher Magic level it grants also raises your magic defence, keeping you tankier.

Melee is a viable alternative if you would rather not mage — the meta there is a Scythe of vitur (or another high-tier slash/stab weapon like Osmumten's fang or a Ghrazi rapier) with full strength gear — but it is generally less efficient than maging with a powered staff. One melee nuance worth knowing: unless you run a Scythe, the recoil from a charged ring of suffering ends up out-damaging what a berserker ring (i) would add, because so much of the fight is spent absorbing hits. Rather than list exact best-in-slot pieces, plug your bank into our Boss Gear Finder above; for the wider style write-ups see our magic gear guide.

For the prayer side, Piety (needs 70 Prayer) is recommended if you go melee, while the Redemption-based supply method needs only 49 Prayer. Either way, 90 Hitpoints is strongly advised — see the supplies section for why. Brush up on the underlying mechanics in our Prayer guide.

Two items are mandatory, not optional: you must wear a gas mask, facemask, or Slayer helmet. Thermy sits in a smoky environment, and without smoke protection you take ongoing damage and your stats get drained — exactly as with every other smoke and dust devil. The Slayer helmet (i) doubles as your best mage helmet here, so it is the natural choice.

Beyond that, your inventory depends on which sustain method you run. A typical magic loadout is a saturated heart (or imbued heart) to boost Magic, a teleport-to-house tablet, a divine rune pouch with your barrage/ice runes, and the rest filled with super restores as needed. The Redemption method instead leans on a stack of zamorak brews (or ancient/forgotten brews) to restore prayer cheaply, plus a menaphite remedy or two to mop up stat reductions, and a little cheap food. Whatever you bring, leave a couple of free slots — or a rune pouch to hold rune drops — so the boss's frequent loot doesn't overflow. Track current prices for any consumable on our GE price tracker.

Thermy is refreshingly simple — it has effectively one attack plus one environmental rule.

The typeless magical ranged attack. Thermy only ever uses a single ranged attack that hits up to 8. Two things make it annoying. First, it is 'typeless', which means protection prayers do nothing — there is no 'Protect from X' that blocks it, so you can't pray it away. Second, it is 'magical ranged': its accuracy is rolled against your magic defence bonus, which is why a mage-defensive setup keeps you alive. The attack is very accurate, fires every 2 ticks (1.2 seconds), and reaches 8 tiles. Because you can't pray against it, all your survivability comes from gear, your sustain method, and positioning.

The smoke (environmental). The whole arena is smoky. If you are not wearing a gas mask, facemask, or Slayer helmet, the smoke itself damages you and drains your stats continuously — so this isn't a phase to react to, it's a kit check you pass before the fight starts.

Range mismatch you can exploit. Your magic spells reach 9 tiles while thermy reaches only 8. Freeze it with an ice spell, then step one tile out of its range and keep attacking from safety — it can't hit back. An Ice ancient sceptre is ideal for this because it adds 10% accuracy against unfrozen targets and extends freeze time; note that powered staves must use the longrange attack style to reach 9 tiles, and the eye of ayak cannot safespot at all.

No conventional safespotting. Unlike most NPCs, thermy can always walk through other monsters and players — Jagex did this deliberately so you can't hide behind the smaller smoke devils in its lair. The freeze-and-step-out trick above is the only true 'safespot', and it relies on the range gap, not on a wall or a body block. This is also why bringing a dwarf multicannon is pointless: the cannon is destroyed the instant you set it up in the room, exactly as at the King Black Dragon and Kalphite Queen.

Pick a sustain method to match your gear and bank. There are four established approaches.

1. Magic + freeze/safespot (the standard). Walk in, freeze thermy with the best ice spell you have, step back a tile so it can't reach you, and DPS it down from 9 tiles. With Tumeken's shadow this is the fastest clear and the closest thing to a no-damage kill. Re-freeze as the timer runs out. This is where the 60–100 kills/hour figure comes from.

2. Blood Barrage healing. If you have strong magic-attack and strength-bonus gear, Blood Barrage can out-heal thermy's damage, letting you chain very long trips. The Ancient sceptre's passive and bloodbark armour support this with little magic loss, and Augury plus a Forgotten brew or imbued heart raise effectiveness. The catch: the wiki notes it runs roughly 2–3x slower than using Tumeken's shadow, and it's only profitable if you hit uniques. Bring plenty of prayer/super restores and a little emergency food for unlucky splash streaks.

3. Redemption method (cheap sustain). With 49+ Prayer, run the Redemption prayer: when your HP drops below 10% it spends your remaining prayer to heal you for 25% of your Prayer level (rounded down). After each trigger, quickly sip a prayer-restoring dose and re-flick Redemption. Because thermy's max hit is 8, you must stay at 9 HP or more at all times so a hit can't kill you before Redemption fires — which is exactly why 90 Hitpoints is recommended. Zamorak/ancient/forgotten brews make this dramatically cheaper than prayer potions; a high-level player can sustain a full trip on zamorak brews alone.

4. Walk-under method (no-mage option). Your attack speed is slower than thermy's, so for each of your hits it gets 2–2.5. By stepping under thermy right after you attack, you hide from its shots until you step out again, cutting damage taken by 50–60%. There's an advanced refinement: NPCs stop moving when the player they're targeting is underneath them and the player clicks a ground item or interactive object (anything that produces a red 'X'). So you can click the ashes thermy drops every kill — or the room door — to lock it in place and settle into a clean 1:1 rhythm. A reliable setup is to stand on thermy's west side, then alternate: attack the boss, click the door, walk the two tiles back under it, and re-attack once you see the XP drop. This is the preferred method for players who don't want to (or can't) mage.

There is also a fast POH/Nardah special-attack method: bring max strength gear and a heavy spec weapon like dragon claws, dump specials to kill thermy almost instantly, then teleport home to a rejuvenation pool (or use a Desert amulet 4 if you've done the elite Desert Diary) to restore HP, prayer and special between kills. It's cheap and high-profit but slower than a clean magic rotation, because the boss has only a short respawn timer and the fight ends so fast that the teleport overhead dominates.

Two DPS extras stack onto any method: casting Resurrect Greater Zombie raises your damage output by around 5%, and because kills are so quick, Death Charge can be re-applied in rapid succession to keep your special-attack energy topped up.

Thermy is the only source in the game for three items, which is the whole reason people fight it: the smoke battlestaff, the jar of smoke, and the pet smoke devil. The smoke battlestaff is the headline grind at a drop rate of 1/512 — a combination staff that's a genuine money-spinner over a task. Beyond the exclusives, thermy drops the occult necklace — a core magic-damage amulet — at a higher rate than the regular smoke devils do, so a smoke devil task is a respectable way to pick one up. The rare dragon chainbody rounds out the marquee unique table. Every single kill also always drops ashes (which, handily, is the ground item you click for the advanced walk-under method). The full drop table with exact rates is shown above; consult it rather than relying on memory.

Trying to fight thermy off-task. The most common wall: you can only attack it on a smoke devil task. No task, no fight (bar the single Western Provinces Diary kill at real 93 Slayer).

Boosting Slayer to 93. A Slayer boost will not let you damage thermy — the level requirement ignores stat boosts entirely.

Forgetting smoke protection. Walking in without a gas mask, facemask, or Slayer helmet means the smoke chips your HP and drains your stats the entire time. Always check this before pulling.

Bringing a cannon. A dwarf multicannon is destroyed the moment you set it up in the room — wasted cannon, wasted trip.

Relying on protection prayers. Thermy's attack is typeless, so there is no overhead prayer that blocks it. Survivability comes from magic defence and your sustain method, not from praying.

Dropping below 9 HP on Redemption. Since the max hit is 8, letting your HP fall under 9 while running Redemption risks a death before the prayer can trigger — keep a buffer and lean on a high Hitpoints level.