Furnace Power

Is Furnace good in Slay the Spire 2?

Furnace is an uncommon Regent power in Slay the Spire 2. In combat it resolves as: At the start of your turn, Forge. It’s a dependable, middle-of-the-pack option, landing at C tier in our rankings.

Across 483 recorded runs, decks running it win 27.5% of the time, comfortably clear of the 13.8% average, by 13.7%. It’s a more selective pick, turning up in just 2.3% of decks that could run it. Taken in 27.5% of its offers, it still trails on the pick-versus-skip split: 27.4% for runs that took it against 30.7% for runs that left it, a -3.2% pick lift over 361 decided runs. Regent players keep it in 14.5% of their runs, so it’s a familiar sight in those decks. On average it shows up 1.4 times in the decks that take it.

It performs best next to Decisions, Decisions — together they post a +24.6% swing in win rate. It also has strong chemistry with the relic Candelabra, which moves its win rate by +31.2%. At 1 energy, it’s upgraded in 41.1% of runs and usually joins the deck around floor 15.

Upgraded, it gains +2 Forge, which is why so many decks invest a rest-site upgrade in it. That’s 132 wins, 348 deaths, and 3 abandoned runs with it in the deck. The encounter that most often ends a run carrying it is Decimillipede Elite, which closes out 6.6% of its appearances. Read on for Furnace’s complete synergy, class, and threat breakdown to decide whether it earns a slot in your Regent run.

Pick or Skip: Furnace

Out of 1581 recorded offers Furnace is taken 27.5% of the time, and taking it is worth -3.2% in pick lift — 27.4% for runs that picked it against 30.7% for runs that skipped, across 361 decided runs.

Taken 435 times out of 1581 offers.

Pick rate when offered counts offers, not runs: out of every time the game put this in front of a player, how often it was taken. It is not the same number as the share of runs that end up containing it.

Pick lift is the sample-adjusted gap between runs that took the option and runs that passed on it. It is the fair way to rank choices, because raw win rates put the smallest samples on top.

When to Pick Up Furnace

Furnace is strongest when it joins the deck in Act 3, where runs win 60.5% across 44 runs — one of 4 recorded pickup windows.

Win rate of runs by the act Furnace entered the deck. Acts that have not reached the sample floor show their run count only.

Best Cards to Pair with Furnace

Ranked by win-rate lift, Furnace performs best alongside Decisions, Decisions (+24.6%), Mad Science (+21.9%), and Big Bang (+20.5%).

Decisions, Decisions+24.6%49 runsMad Science+21.9%30 runsBig Bang+20.5%104 runsVoid Form+20.2%87 runsTyranny+20.1%21 runsProphesize+19.5%16 runs

Based on small co-occurring samples — treat these as early signals, not final verdicts.

Furnace Win Rate by Class

Furnace is drafted only by the Regent, where it holds a 27.4% win rate across 478 runs.

The Regentappears in 14.5% of its runs (478 tracked)

Best Relics for Furnace

Furnace pairs best with the relics Candelabra (+31.2%), Vajra (+29.5%), and Orichalcum (+28.6%), ranked by win-rate lift.

Candelabra+31.2%39 runsVajra+29.5%72 runsOrichalcum+28.6%44 runsTungsten Rod+28.3%20 runsStone Calendar+28.3%20 runsMercury Hourglass+26.0%40 runs

Based on small co-occurring samples — treat these as early signals, not final verdicts.

Furnace Card Details

Furnace is an uncommon power costing 1 energy; it’s upgraded in 41.1% of runs and usually picked up by floor 15.

At the start of your turn, Forge.

Upgrade: +2 Forge

What Ends Runs with Furnace

Furnace’s most common run-enders are Decimillipede Elite (6.6%), Knowledge Demon Boss (4.8%), and Kaiser Crab Boss (4.6%).

• Decimillipede Elite6.6% of runs
• Knowledge Demon Boss4.8% of runs
• Kaiser Crab Boss4.6% of runs
• Test Subject Boss4.1% of runs
• Queen Boss3.7% of runs

See Also

Compare Furnace with the rest of the best Slay the Spire 2 cards, relics, and classes below.