Breakthrough•Attack

Is Breakthrough good in Slay the Spire 2?

Breakthrough is a common Ironclad attack in Slay the Spire 2. In combat it resolves as: Lose 1 HP. Deal 9 damage to ALL enemies. It’s a dependable, middle-of-the-pack option, landing at C tier in our rankings.

Across 153 recorded runs, decks running it win 29.4% of the time, comfortably clear of the 19.0% average, by 10.4%. It’s a more selective pick, turning up in just 4.0% of decks that could run it. Ironclad players keep it in 21.5% of their runs, so it’s a familiar sight in those decks. On average it shows up 1.3 times in the decks that take it.

It performs best next to Vicious — together they post a +20.3% swing in win rate. It also has strong chemistry with the relic Regal Pillow, which moves its win rate by +34.7%. At 1 energy, it’s upgraded in 17.6% of runs and usually joins the deck around floor 10.

Upgraded, it gains +4 Damage, which is why so many decks invest a rest-site upgrade in it. That’s 37 wins, 89 deaths, and 27 abandoned runs with it in the deck. The encounter that most often ends a run carrying it is The Insatiable Boss, which closes out 5.9% of its appearances. Read on for Breakthrough’s complete synergy, class, and threat breakdown to decide whether it earns a slot in your Ironclad run.

Best Cards to Pair with Breakthrough

Ranked by win-rate lift, Breakthrough performs best alongside Vicious (+20.3%), Pact's End (+20.2%), and Rupture (+19.4%).

Vicious+20.3%12 runsPact's End+20.2%6 runsRupture+19.4%46 runsFlash of Steel+16.9%5 runsVolley+16.3%3 runsRegret+16.3%3 runs

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

Breakthrough Win Rate by Class

Breakthrough is played across 2 classes, led by Ironclad (29.6%) and Silent (0.0%) by win rate.

The Ironclad29.6%152 runsThe Silent0.0%1 runs

Best Relics for Breakthrough

Breakthrough pairs best with the relics Regal Pillow (+34.7%), Gnarled Hammer (+23.5%), and Lord's Parasol (+23.5%), ranked by win-rate lift.

Regal Pillow+34.7%23 runsGnarled Hammer+23.5%6 runsLord's Parasol+23.5%5 runsBag of Marbles+22.5%13 runsSparkling Rouge+20.3%10 runsFresnel Lens+20.3%9 runs

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

Breakthrough Card Details

Breakthrough is a common attack costing 1 energy; it’s upgraded in 17.6% of runs and usually picked up by floor 10.

Lose 1 HP. Deal 9 damage to ALL enemies.

Upgrade: +4 Damage

What Ends Runs with Breakthrough

Breakthrough’s most common run-enders are The Insatiable Boss (5.9%), Ceremonial Beast Boss (4.6%), and Test Subject Boss (4.6%).

• The Insatiable Boss5.9% of runs
• Ceremonial Beast Boss4.6% of runs
• Test Subject Boss4.6% of runs
• Knowledge Demon Boss4.6% of runs
• Queen Boss3.3% of runs

See Also

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