Furnace

Furnace is a 4-Elixir mobile troop that walks toward the enemy while firing its own ranged attack and periodically launching kamikaze Fire Spirits that detonate for area damage against air or ground targets. Its Evolution dramatically speeds up spirit production while actively attacking, at the cost of the Furnace's own movement speed. Originally a stationary spawner building with no attack of its own, it was rebuilt into this troop form in an August 2025 rework and has been tuned several times since — most recently, an August 2026 patch that weakened every Spirit-type card's hitpoints also sped Furnace's own spawn rate back up as direct compensation, on top of a separate June 2026 cut to its attack range.

• Furnace costs 4 Elixir and fields a single ranged attacker with 727 hitpoints that deals 179 damage per hit every 1.8 seconds, working out to about 99 damage per second. It walks at Medium speed, strikes both air and ground targets out to a 5.5-tile range, and deploys in 1 second like most troops.

• While it's out on the field moving or fighting, Furnace launches a Fire Spirit every 5 seconds. Each spirit sprints toward the nearest target and detonates on impact for 207 area damage against air or ground, then is gone — a one-shot kamikaze unit with 215 hitpoints of its own, built to clear the battlefield rather than stick around and trade hits.

• Every Fire Spirit Furnace spawns moves at Very Fast speed, literally double the Furnace's own Medium walking pace, so spirits always race ahead and reach the fight well before their parent Furnace catches up. In effect, Furnace advances behind a rolling stream of fast explosive scouts rather than fighting alongside them.

• EvolutionEvolved Furnace gains a 'Hot Spawns' effect — while it's actively attacking, it launches a new Fire Spirit every 2.4 seconds instead of the usual 7, nearly three times as often, alternating which side each spirit pops out of, and keeps up that faster pace for one extra spirit even after it stops attacking. The trade-off is mobility: Evolved Furnace only moves at Slow speed, noticeably slower than a regular Furnace's Medium walk. Like other Evolutions, it needs to recharge — after it's used, you have to play two regular Furnaces before the evolved version is ready again, so roughly one in every three Furnaces you drop comes out evolved.

• Furnace used to be a stationary building that could only spawn Fire Spirits and had no attack of its own. Supercell rebuilt it into a mobile troop in the August 2025 'Fired Up' update, giving it a direct ranged attack for the first time in the card's history alongside its Fire Spirit spawning, and having it walk toward the fight instead of sitting in place.

• Days after that troop rework launched, Supercell hit Furnace with an emergency nerf because it was 'performing a bit too well': hitpoints dropped from 896 to 727 and the Fire Spirit spawn interval slowed from every 5 seconds to every 7 seconds, 40% longer between spirits.

• A June 2026 balance update cut Furnace's range from 6 tiles down to 5.5, about an 8% reduction. Supercell's reasoning was that the card's long range combined with its constant Fire Spirit output let it fight from too safe a distance, so shrinking its reach pushed it closer to real danger.

• In an August 2026 balance pass, Supercell cut the hitpoints of every Spirit-type unit in the game by 6%, including the Fire Spirits Furnace spawns, following a community vote on whether Spirits should lose health or speed. To offset the weaker spirits, non-Evolution Furnace's own spawn rate was sped back up from every 7 seconds to every 5, about 29% faster, as direct compensation.