Flak Cannon•Attack

Is Flak Cannon good in Slay the Spire 2?

Flak Cannon is a rare Defect attack in Slay the Spire 2. In combat it resolves as: Exhaust ALL your Status cards. Deal 8 damage to a random enemy for each card Exhausted. It ranks among the strongest cards its class can draft right now, earning a spot at S tier in our Slay the Spire 2 card tier list.

Across 23 recorded runs, decks running it win 42.9% of the time, comfortably clear of the 18.9% average, by 23.9%. It’s a more selective pick, turning up in just 0.6% of decks that could run it. Defect players keep it in 3.9% of their runs, so it’s a familiar sight in those decks. On average it shows up 1.1 times in the decks that take it.

It performs best next to Fusion — together they post a +16.3% swing in win rate. It also has strong chemistry with the relic Bag of Marbles, which moves its win rate by +19.1%. At 2 energy, it’s upgraded in 30.8% of runs and usually joins the deck around floor 18.

Upgraded, it gains +3 Damage, which is why so many decks invest a rest-site upgrade in it. That’s 9 wins, 12 deaths, and 2 abandoned runs with it in the deck. The encounter that most often ends a run carrying it is Kaiser Crab Boss, which closes out 8.7% of its appearances. Read on for Flak Cannon’s complete synergy, class, and threat breakdown to decide whether it earns a slot in your Defect run.

Best Cards to Pair with Flak Cannon

Ranked by win-rate lift, Flak Cannon performs best alongside Fusion (+16.3%), Smokestack (+15.2%), and Synchronize (+13.2%).

Fusion+16.3%4 runsSmokestack+15.2%6 runsSynchronize+13.2%3 runsProduction+13.2%3 runsHologram+11.3%10 runsModded+9.5%3 runs

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

Flak Cannon Win Rate by Class

Flak Cannon is drafted only by the Defect, where it holds a 42.9% win rate across 23 runs.

The Defectappears in 3.9% of its runs (23 tracked)

Best Relics for Flak Cannon

Flak Cannon pairs best with the relics Bag of Marbles (+19.1%), Red Mask (+17.6%), and Regal Pillow (+15.2%), ranked by win-rate lift.

Bag of Marbles+19.1%5 runsRed Mask+17.6%7 runsRegal Pillow+15.2%7 runsCloak Clasp+13.2%3 runsVajra+13.2%4 runsJoss Paper+13.2%3 runs

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

Flak Cannon Card Details

Flak Cannon is a rare attack costing 2 energy; it’s upgraded in 30.8% of runs and usually picked up by floor 18.

Exhaust ALL your Status cards. Deal 8 damage to a random enemy for each card Exhausted.

Upgrade: +3 Damage

What Ends Runs with Flak Cannon

Flak Cannon’s most common run-enders are Kaiser Crab Boss (8.7%) and Infested Prisms Elite (8.7%).

• Kaiser Crab Boss8.7% of runs
• Infested Prisms Elite8.7% of runs

See Also

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