What Is a Synergy?
A synergy is when two or more cards, relics, or effects combine to produce an outcome greater than the sum of their individual parts. In STS2, building and recognizing synergies is the difference between a run that clears Act 3 and one that dies in Act 2.
Three synergy categories:
| Type | Description | Example |
|---|---|---|
| Combo Synergy | Two cards played together in the same turn for an explosive effect | Limit Break + Demon Form |
| Engine Synergy | A self-sustaining loop that compounds value automatically each turn | Dark Embrace + Exhaust cards |
| Infinite Loop | Specific conditions under which cards can cycle indefinitely | Corruption + Dark Embrace + Feel No Pain |
How Infinite Loops Work
Every infinite combo must satisfy three conditions simultaneously. If any condition breaks, the loop stops.
| Condition | What It Means |
|---|---|
| 1. Net zero energy | One full cycle of the loop costs 0 or negative Energy total |
| 2. Draw sustain | At least 1 card is drawn for every 1 card played in the cycle |
| 3. Payoff | At least one card in the loop generates damage or Block |
When evaluating a potential infinite, verify all three conditions explicitly. Loops that satisfy 2 out of 3 only work a finite number of times.
Confirmed Infinite Combos
Ironclad: Exhaust Loop
Required cards: Corruption + Dark Embrace + Feel No Pain
| Card | Effect |
|---|---|
| Corruption (Power) | All Skills cost 0 but Exhaust on play |
| Dark Embrace (Power) | Draw 1 card whenever a card is Exhausted |
| Feel No Pain (Power) | Gain 3 Block whenever a card is Exhausted |
How the loop works:
- Corruption makes all Skills free and forces Exhaust on play
- Play any Skill → it Exhausts → Dark Embrace draws 1 → Feel No Pain adds 3 Block
- The drawn card (if a Skill) costs 0 and triggers the same chain
- Continues until no Exhaust-triggering Skills remain in the deck
Result: Infinite Block equal to 3 × (number of Skill cards in deck). Adding Exhaust-synergy Skills like Sever Soul maximizes the block ceiling. This is one of the most consistent win conditions in Ironclad.
Defect: Claw Loop
Required cards: Multiple copies of Claw + All for One
| Card | Effect |
|---|---|
| Claw (0-cost Attack) | Deals damage. Permanently increases all Claws' base damage by 2 for each Claw played this turn (even across all copies) |
| All for One (2-cost Attack) | Add every 0-cost card from the discard pile to your hand; deal damage |
| Scrape (1-cost Attack) | Deal 4 damage, draw 4 — draws 0-cost cards including Claws back into hand |
How the loop works:
- Play Claws — each additional Claw played this turn increases all Claws' base damage by 2
- All for One recovers all Claws from the discard pile into hand
- Play Claws again — damage escalates because base damage accumulated from the previous chain
- Repeat: each All for One cycle multiplies the base damage
Result: Not a true infinite, but damage scales exponentially each cycle. Two or three cycles of All for One typically produces enough damage to kill any boss in 1–2 turns.
Silent: Sly Infinite Loop
Required cards: Tools of the Trade + multiple Sly keyword cards
| Card | Effect |
|---|---|
| Tools of the Trade (Power) | Draw 1 and discard 1 at turn start — free, no Energy cost |
| Sly cards | "When discarded from hand during your turn, play this card for free" |
How the loop works:
- Tools of the Trade forces a discard at the start of every turn
- If the discarded card has the Sly keyword, it triggers for free without spending Energy
- Many Sly cards also force draws or additional discards, chaining into more Sly triggers
- A dense enough concentration of Sly cards creates near-infinite free plays per turn
Result: Highly dependent on the density of Sly cards in the deck. At high Sly density, this produces dozens of free card activations per turn, generating enormous damage or Block without spending Energy.
Core 2-Card Combos by Character
Ironclad
Combo 1: Barricade + Body Slam
| Card | Effect |
|---|---|
| Barricade | Block does not expire at turn end |
| Body Slam | Deal damage equal to current Block (Upgraded: no longer Exhausts) |
How to use: After Barricade is live, every Block card you play simultaneously increases your defense AND your next Body Slam's damage. At 50 Block, Body Slam deals 50 damage. At 100 Block over multiple turns, Body Slam one-shots most bosses.
Supporting cards: Juggernaut (deal 5 damage whenever you gain Block — passive offense from every Block action), Entrench (double current Block — spike turn enabler)
Combo 2: Demon Form + Limit Break (Strength Scaling)
| Card | Effect |
|---|---|
| Demon Form | Gain +2 Strength per turn (+3 upgraded) permanently |
| Limit Break | Double current Strength (Upgraded: no longer Exhausts — repeat every turn) |
How to use: Let Demon Form accumulate Strength for 2–3 turns, then apply Limit Break. Upgraded Limit Break applies each turn, compounding exponentially: 4 → 8 → 16 → 32 Strength in just a few turns. Multi-hit cards (Whirlwind, Sword Boomerang) multiply every Strength point across all hits.
Combo 3: Echo Form + High-Value Card
| Card | Effect |
|---|---|
| Echo Form | The first card you play each turn plays twice (3-cost Power) |
How to use: Echo Form doubles the effect of whatever card you lead with. On Glacier (Defect): 12 Block + 4 Frost channels from a single card. On Ball Lightning: 14 damage + 2 Lightning channeled. On any draw card: effectively draw 2 instead of 1 with no extra cost.
Silent
Combo 1: Accuracy (×3–4) + Shiv Generation
| Card | Effect |
|---|---|
| Accuracy | +4 damage per copy to every Shiv. Stacks multiplicatively |
| Infinite Blades | Add 1 Shiv to hand each turn (Power) |
| Blade Dance | Add 3 Shivs to hand |
How to use: Each Accuracy copy adds +4 to every Shiv's base damage. 4 copies of Accuracy → each Shiv deals 3+16=19 damage. With 10–15 Shivs generated per turn, total output reaches 190–285 damage.
Supporting cards: After Image (gain 1 Block per card played — Shiv spam becomes simultaneous defense), Storm of Steel (convert entire hand to Shivs + draw)
Combo 2: Burst + Catalyst (Poison Detonation)
| Card | Effect |
|---|---|
| Burst | The next Skill you play triggers twice |
| Catalyst | Double enemy's Poison stacks (Upgraded: ×3) |
How to use: Stack Poison to 20–30, then chain Burst → Catalyst → Catalyst. 20 stacks: ×2 = 40, then ×2 = 80. Next turn the enemy takes 80 damage from Poison alone. With upgraded Catalyst: 20 → 60 → 180. One of the highest burst damage ceilings in the game.
Defect
Combo 1: High Focus + Frost Orb Passive Defense
| Card | Effect |
|---|---|
| Defragment | +1 Focus (+2 upgraded) permanently |
| Frost Orb | While in a slot, generates (3 + Focus) Block at turn start passively |
How to use: At Focus 5, each Frost Orb generates 8 Block per turn automatically. Fill all three Orb slots with Frost: 24 Block per turn from passive generation alone. Combine with Coolheaded (Channel 1 Frost + draw 1) to refill Orbs efficiently.
Combo 2: Electrodynamics + Lightning Orb
| Card | Effect |
|---|---|
| Electrodynamics (Power) | Lightning Orb Evokes hit all enemies instead of one |
| Lightning Orb Evoke | Deals (8 + Focus) damage — becomes AoE with Electrodynamics |
How to use: Once Electrodynamics is live, every Lightning Evoke clears entire rooms. Multi-Cast (Evoke the current Orb X times) with Electrodynamics = (8+Focus) × X damage to all enemies simultaneously.
Necrobinder
Combo 1: Doom Stack + End of Days (Execute)
| Card | Effect |
|---|---|
| No Escape | Apply Doom 10; +5 Doom per 10 existing Doom stacks (scales with own stacks) |
| End of Days | Apply Doom 29; instantly kill any enemy whose HP ≤ their Doom count |
How to use: Use No Escape and other Doom appliers to push a target's Doom above their current HP. End of Days both stacks significant Doom AND triggers the execute check. Because Doom-death bypasses Block, this mechanic works against heavily armored enemies that resist conventional damage.
Critical rule: Do not mix Doom, Osty, and Soul builds. Each scales on different resources — a hybrid deck dilutes all three and performs worse than any pure archetype.
Combo 2: Calcify + Osty Attack Chain
| Card | Effect |
|---|---|
| Calcify | Osty's damage +4 for N attacks. Multiple copies stack |
| Squeeze | +5 damage per Osty attack card played in sequence |
How to use: Pre-stack Calcify before initiating an Osty attack chain. With 3 Calcify stacks, Osty's base damage increases by 12. With 2 Squeeze, each additional Osty attack in the chain deals +10 more damage. A 5-card Osty chain with this setup deals dramatically more damage than the cards' base values suggest.
Regent
Stars Accumulation + Finisher
| Resource | How It Works |
|---|---|
| Stars | Second resource alongside Energy. Starts at 3 per combat, max 24 |
| Star generators | 0–1 Energy cards that produce Stars efficiently |
| Star finishers | Cards costing significant Stars + Energy that deal massive damage or effects |
How to use: Dedicate 1–2 turns to generating Stars with cheap actions, then align a turn with enough Energy and Stars to fire the finisher. Never overflow the 24-Star cap — that is wasted generation. The core skill is planning 2–3 turns ahead to ensure Stars and Energy are both available when the finisher lands.
Universal Synergies (All Characters)
Vulnerable Synergy
Vulnerable is the most powerful universal debuff — enemies affected take 50% more damage from all attacks.
| Role | Primary Sources |
|---|---|
| Enablers (apply Vulnerable) | Bash (Ironclad), Bouncing Flask, various Potions |
| Payoffs (capitalize on Vulnerable) | Every high-damage attack card in your deck |
Rule: Multiple Enabler cards do not synergize with each other. The correct ratio is 1–2 Enablers and 3–5 high-damage Payoffs.
Strength Scaling
Strength adds directly to all attack card damage, making it the simplest and most linear scaling mechanic.
| Source | Effect |
|---|---|
| Vajra (Relic) | +1 Strength at combat start every fight |
| Demon Form (Power) | +2–3 Strength per turn permanently |
| Inflame (Power) | Immediate +2 Strength |
| Limit Break (Skill) | Double current Strength |
Math example: Strength 10 + Whirlwind at 3 Energy (3 uses × 3 damage + 10 Strength per hit = 13 per hit × 3 hits = 39 damage per enemy, all-targets). Three enemies: 117 damage in one card.
Draw Acceleration
Thin decks need draw acceleration to see key cards every turn. 0-cost draw cards are the highest-value filler picks.
| Card | Effect | Value |
|---|---|---|
| Prepared | 0-cost, draw 1, discard 1 | Net 0 cost for card filtering |
| Offering | 0-cost, draw 2, lose 6 HP | 2 free draws at HP cost |
| Acrobatics | Draw 3, discard 1 | Net +2 cards for 1 Energy |
| Scrape | 1-cost, deal 4, draw 4 | Combines offense and draw; exceptional value |
Principle: A 15-card deck with 2–3 draw-acceleration cards effectively cycles the entire deck every turn. At this density, every key synergy card appears in your hand every rotation.
Common Synergy Building Mistakes
1. Wrong Enabler-to-Payoff Ratio
Stacking 5 Vulnerable-applying cards with only 1 damage card means the payoff fires once. Conversely, 5 high-damage cards with no Vulnerable access means 1.5× damage never activates.
Correct ratio: 1–2 enablers, 3–5 payoffs.
2. Mixing Multiple Build Concepts
A deck trying to do Strength scaling, Poison buildup, and Exhaust loops simultaneously does all three at 30% effectiveness.
Rule: Commit to one direction by the end of Act 1 and stop adding cards that don't support it.
3. Waiting for the Full Combo Before Playing Offense in Act 1
Combos come online in Act 2. Act 1 requires immediately functional cards to survive.
Rule: Take cheap, immediately functional cards in Act 1. Build toward the combo, not from it.
4. Forgetting Relic Synergies
Relics often double or triple a combo's effectiveness:
- Shuriken (3 attacks/turn → +1 Strength) transforms Shiv builds into permanent Strength engines
- Paper Phrog (increases Vulnerable damage multiplier) makes Vulnerable-centric builds deal 175% instead of 150% per attack
Rule: Every time you pick up a Relic, immediately evaluate whether it modifies your current build's core synergy.
The Synergy-Building Process
- Lock in a core card — when you see a powerful card with scaling potential, commit early ("This run is Demon Form Strength — go")
- Identify what the core card needs — what enablers, payoffs, and removal are required to make it functional?
- List the cards that fulfill those needs — prioritize them on every card-reward screen
- Remove cards that dilute the core — aggressive removal of non-synergistic cards is more valuable than adding new ones
- Check relics for hidden multipliers — relic interactions with your core combo are frequently the difference between S-tier and B-tier power levels
Synergies are built deliberately, not discovered by accident. Deciding which synergy to pursue before the end of Act 1 is the single highest-leverage decision in a run.
Based on Early Access data. Card effects and synergy evaluations may change with balance patches.