Signal Boost•Skill

Is Signal Boost good in Slay the Spire 2?

Signal Boost is a rare Defect skill in Slay the Spire 2. In combat it resolves as: The next Power you play is played an additional time. It’s a dependable, middle-of-the-pack option, landing at C tier in our rankings.

Across 53 recorded runs, decks running it win 33.3% of the time, comfortably clear of the 18.9% average, by 14.4%. It’s a more selective pick, turning up in just 1.4% of decks that could run it. Ironclad players keep it in 0.4% of their runs, so it’s a familiar sight in those decks. On average it shows up 1.2 times in the decks that take it.

It performs best next to Rocket Punch — together they post a +18.5% swing in win rate. It also has strong chemistry with the relic Red Mask, which moves its win rate by +15.8%. At 1 energy, it’s upgraded in 35.5% of runs and usually joins the deck around floor 16.

Upgraded, it gains -1 EnergyCost, which is why so many decks invest a rest-site upgrade in it. That’s 15 wins, 30 deaths, and 8 abandoned runs with it in the deck. The encounter that most often ends a run carrying it is Kaiser Crab Boss, which closes out 5.7% of its appearances. Read on for Signal Boost’s complete synergy, class, and threat breakdown to decide whether it earns a slot in your Defect run.

Best Cards to Pair with Signal Boost

Ranked by win-rate lift, Signal Boost performs best alongside Rocket Punch (+18.5%), Boost Away (+18.2%), and Genetic Algorithm (+15.7%).

Rocket Punch+18.5%10 runsBoost Away+18.2%14 runsGenetic Algorithm+15.7%7 runsScrape+15.6%7 runsHailstorm+12.5%7 runsEcho Form+11.9%4 runs

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

Signal Boost Win Rate by Class

Signal Boost is played across 3 classes, led by Ironclad (100.0%), Defect (30.9%), and Necrobinder (0.0%) by win rate.

The Ironclad100.0%3 runsThe Defect30.9%49 runsThe Necrobinder0.0%1 runs

Best Relics for Signal Boost

Signal Boost pairs best with the relics Red Mask (+15.8%), Meal Ticket (+15.7%), and Joss Paper (+15.4%), ranked by win-rate lift.

Red Mask+15.8%10 runsMeal Ticket+15.7%7 runsJoss Paper+15.4%4 runsHappy Flower+12.5%6 runsAmethyst Aubergine+12.5%6 runsGame Piece+11.9%5 runs

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

Signal Boost Card Details

Signal Boost is a rare skill costing 1 energy; it’s upgraded in 35.5% of runs and usually picked up by floor 16.

The next Power you play is played an additional time.

Upgrade: -1 EnergyCost

What Ends Runs with Signal Boost

Signal Boost’s most common run-enders are Kaiser Crab Boss (5.7%), Test Subject Boss (5.7%), and Infested Prisms Elite (3.8%).

• Kaiser Crab Boss5.7% of runs
• Test Subject Boss5.7% of runs
• Infested Prisms Elite3.8% of runs
• Entomancer Elite3.8% of runs
• Knights Elite3.8% of runs

See Also

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