The Slowest Clock in the Game Is Also the Most Reliable
Meet the Tunneler, an 87 HP Act 2 normal. It bites for 13, then burrows behind 32 Block that never decays, and strikes from below for 23 every turn after, per our bestiary. Attack decks have to crack that Block shell, and the bestiary tip amounts to hoping: either save burst to break the Block for a stun or settle in and block 23 forever. A Poison deck does neither. The count on the Tunneler keeps climbing while it hides, because stacks tick as a debuff on the enemy rather than as an attack from you, and the shell it spent a turn building does not slow the clock by a second.
That is the identity of the archetype: trade burst for inevitability. Our build table rates Poison Stacking A tier at difficulty 2 out of 5, and the database entry describes it with three honest clauses, extremely consistent, slow against high-HP bosses, and great in co-op. All three are true at once, and this guide spends its time on the second clause, because slow is only a problem you can lose to if you have not done the math in advance. Done right, the poison deck knows which turn the boss dies on before the fight starts.
The core, straight from the build entry: stack Poison up, then double or triple it with Catalyst, with Wraith Form as the defensive closer. The engine card is Noxious Fumes, the multiplier is Catalyst, and the shield that buys the last few turns is Wraith Form, a rare our card database flags as raised to StS2's new Ancient rarity tier, strong enough that any Silent deck can splash it.
Version anchoring matters more for this deck than most, because the package just moved. v0.110 reworked the Silent poison suite outright, redesigning Haze, Outbreak and Mirage and removing Mirage's Exhaust clause, and v0.111 beta layered another balance pass on top. Names and numbers in this guide reflect the v0.111 card and enemy database; anything that shifts on the next beta patch will shift in our status effects and card database pages first.
One framing note before the engine cards. Poison is not attack damage, and that distinction does real work in both directions. Your own Vulnerable sources do nothing for your ticks, since Vulnerable only amplifies attack damage per our glossary, which changes what you draft relative to an Ironclad. Enemy debuffs pointed at you, like the Owl Magistrate's Verdict for 33 plus 4 Vulnerable, amplify the hits you take, not the ticks you give. The deck plays a different resource game than every attack archetype, and the whole strategy follows from that.
Noxious Fumes: One Energy for Poison on Every Enemy, Forever
Noxious Fumes is a 1-cost uncommon Power: at the start of each of your turns, apply 2 Poison, 3 when upgraded, to ALL enemies. Our card database calls it the 1-cost engine of Poison decks, and it is difficult to overstate how much work that one energy does. One payment, income every turn, applied to every body on the field simultaneously, with no further input from you for the rest of the fight.
The income table is the foundation of every plan in this guide. Unupgraded, 2 stacks per turn means about 10 stacks applied in your first five turns of income and 20 in ten, on every enemy at once. Upgraded, 3 per turn reaches 15 applied in five. With Snecko Skull, the Common Silent relic that adds 1 stack to every Poison application, the effective rates become 3 and 4 per turn, and the relic enters mandatory-pick territory our own data assigns it.
The ALL clause is half the card's value. Entomancer summons bees all fight, and every bee ticks. The Kaiser Crab is two claws at 209 and 199 HP, and both claws tick from the same single cast. The Kin puts a priest and two acolytes on the field, and your one engine card is already working on all three while attack decks divide their resources three ways. Multi-enemy fights, normally the tax on slow decks, are where Fumes quietly overperforms.
Play pattern is simple and worth stating firmly: cast it on turn one in almost every fight. It is one energy, it does not need a window, and every turn it sits in your hand is a turn of income lost forever, since Poison cannot be back-dated. The Bygone Effigy, the 127 HP elite that cycles between asleep and awake, is the emblem case: our bestiary tip is to set up powers during the sleep phase, and Fumes ticking through the whole nap is the single best value play in the act.
One matchup nuance the card creates, and it is a real one. The Decimillipede's three segments Reattach at 25 HP whenever a segment dies while the others live, and our bestiary explicitly warns that AoE is a trap in that fight. Fumes applies to all segments equally, which pushes all three toward death on neighboring turns; that is either the safest pattern, since they die almost together, or a disaster, depending on spacing. The fix is targeting: use your direct applications and Catalyst on a single segment to control the kill order yourself, and let the passive income handle the background math.
Upgrade priority is the easiest decision in Silent's kit. Moving Fumes from 2 to 3 per turn lifts the entire engine by half again, and the raise applies to every fight left in the run. It is the first campfire upgrade in almost every version of this deck.
Deadly Poison, Catalyst and Doubling at the Peak
The build entry names the core trio as Deadly Poison plus Catalyst plus Wraith Form, and splits the work cleanly: Deadly Poison stacks, Catalyst multiplies, Wraith Form survives. Deadly Poison is the direct applier, the card that puts a real chunk of stacks on one target now, when you need the count to move on your schedule rather than the engine's. Its role is starting counts and topping off specific targets, most importantly the segment or claw or acolyte you have chosen to kill first.
Catalyst is the finisher, a 1-cost rare: double an enemy's Poison, or triple it when upgraded. Our card entry calls it exactly that, and the entire skill of the archetype lives in its timing, because doubling is a multiplicative act and the base you double decides everything. Doubling 5 stacks makes 10, which is a rounding error against a 240 HP boss. Doubling 20 makes 40, which is a kill button. The same card, the same energy, a factor-of-four difference in outcome.
The peak rule: pop Catalyst when the current stack count is high and the remaining enemy HP fits inside the post-doubling budget. Concretely, run the numbers before the fight. If the boss has about 200 HP left and your count reads 15, doubling to 30 puts the fight away several turns earlier than letting income grind it out. If the count reads 6, doubling is a waste of a rare; block instead, let Fumes work, and hold the Catalyst for three more turns. Decay makes waiting past the peak strictly bad, so the decision window is always know, hold, fire, and the math section next gives you the tables to know with.
Finding Catalyst mid-fight is its own problem, since it is a rare you need on a specific turn. Adrenaline, 0-cost draw plus energy that our database notes fits virtually every Silent deck, is the standard solution: it digs for the Catalyst and pays for it in the same turn. The Duplicator potion, which makes the next card you play resolve twice, converts one Catalyst into two doublings, 20 to 40 to 80; our potion library's stated use for the bottle, hold it for your finisher or a core Power, describes this deck to the letter.
One sequencing trap to write on your hand: Catalyst the turn you apply, not the turn before. Applying 5 more stacks first and then doubling applies the multiplier to the larger number, and the order costs the same energy either way. Every point you add before multiplying is a point that gets multiplied, so the correct pattern in every kill sequence is apply, apply, double.
And one honesty note: a deck of only multipliers is dead weight. Two Catalysts with no engine underneath are two rares that double zero. The engine comes first, in draft order and in play order, every single run.
Poison Math: Stacks, Decay and Turns to Kill Any Boss
Here is the planning model, and it is worth internalizing because it converts the archetype's biggest weakness, slowness, into a schedule. The classic Poison loop, carried over from the first game and still the budgeting rule in v0.111 beta: at the end of the enemy's turn it takes damage equal to its current Poison count, then the count falls by one. Stacks deal their number, then shed one, so a one-shot application of N stacks deals N plus N minus 1 plus N minus 2, down to 1. That is the triangular number, N times N plus 1 over 2, and it is the total damage a single application will ever produce.
The table, with enemy HP pools from our bestiary for reference. 10 stacks is about 55 total damage. 16 stacks is 136, which is effectively the Terror Eel's 140 HP and the Bygone Effigy's 127. 20 stacks is 210, nearly the Soul Fysh's 211. 22 stacks is 253, comfortably the Waterfall Giant's 240. 25 stacks is 325, which covers the Knowledge Demon's 321 before its self-healing. 30 stacks is 465, and at that point you are poisoning things for sport. Read the table the other way for the practical version: look up the boss's HP, find the smallest N whose triangular number clears it, and that is your stack target for the fight.
Now the income side, which is how you know when you will reach the target. Decay shaves one stack per turn, so unupgraded Fumes grows the standing count by only about one per turn, and pure passive income needs roughly fifteen turns to clear a 140 HP elite. That is far too slow for anything with a damage pattern, and it is why the deck is never just Fumes: direct applications from Deadly Poison-class cards front-load the count, Snecko Skull raises every application by 1, and Catalyst multiplies the total you have reached. The engine's whole job is compressing fifteen turns of ticking into five or six, and the worked example below is what that compression looks like.
Worked example against the Waterfall Giant, 240 HP. Target 22 stacks. Turn 1, Fumes. Turns 2 to 4, keep casting: passive income plus two direct applications puts the live count in the mid-teens. Turn 5, Catalyst doubles it past 25, clearing the 253 damage budget, and the Giant dies inside its own loop while you block. That is the whole archetype in one paragraph: count the HP, pick the turn, arrive on time.
Two caveats for precision. Decay and tick order can shift between beta patches, so verify the exact numbers in your build when a patch lands; the ratios are what matter and they are stable. And heal mechanics change the algebra: the Knowledge Demon heals itself, which means your effective target is higher than its printed HP, so add a margin or a second doubling rather than trusting the raw table.
Wraith Form: Two Turns of Near-Immunity to Close the Clock
Poison's structural weakness is the middle of the fight, the turns between ignition and death, when your damage is already locked in but you still have to survive the enemy's pattern. Wraith Form exists to delete those turns. The card, per our database: 3-cost rare Power, gain 2 Intangible, 3 when upgraded, and lose 1 Dexterity at the start of each turn. And the database adds the StS2 twist: it has been raised to the new Ancient rarity tier, described as a defensive answer any deck can splash.
Intangible, from our glossary: all damage taken reduced to 1. Not mitigated, not reduced by half, reduced to one. Two turns of it means the enemy's two biggest telegraphs cost you a combined 2 HP. Mecha Knight's 35-damage Heavy Cleave, the hit our bestiary says to hold 40-plus Block against, becomes a 1. Soul Nexus's 29-damage Soul Burn opener becomes a 1. The Owl Magistrate's 33-plus-4-Vulnerable Verdict becomes a 1 with a debuff attached. There is no other effect in the game that flattens damage patterns this completely, and it stacks conceptually with your poison plan: the ticks keep working while you stand there taking single digits.
The signature use case is the Waterfall Giant, and it is worth walking through because it is the archetype's showcase fight. The Giant's bar fills with Steam Eruption stacks as it acts, and at 0 HP it turns invulnerable, clears all debuffs, your entire poison count included, then self-destructs the following turn for damage equal to its stacks. Our bestiary tip: save your best Block and potions for the explosion turn, Poison is excellent into this fight, and Weak does not reduce the blast. Wraith Form is the cleanest answer in the game to that explosion: cast it on the invulnerability turn, and the self-destruct, unblockable in practice for most decks, costs you 1 HP while your freshly re-applied stacks finish the job.
Timing discipline decides whether the card is a closer or a liability. The Dexterity loss is real and compounding, 1 per turn for the rest of the fight, so casting early turns your defense into Swiss cheese by the end. Cast it late, after the poison count is already lethal-in-progress, and treat the following turns as pure defense, which matches our glossary's blunt instruction for Intangible turns: defend, don't attack. The upgrade from 2 to 3 Intangible is often the difference between covering the death window and running out of ghosts one turn early; it is a legitimate campfire priority once your engine upgrades are done.
The budget version, for runs that never see the rare: Ghost in a Jar, the Silent potion granting 1 Intangible, listed in our potion data as the tool to tank a single turn of massive incoming damage. One blast turn answered for zero energy is exactly what the jar is for.
What You Must Own Before Each Act Gate
Poison runs are won and lost at gates, the specific fights that check whether your deck has the pieces it needs by then. Draft backwards from the gates and the pick order writes itself.
Before the first elite, roughly floors 5 to 8: two or three real damage cards. This is the counterintuitive one, because it means passing early Poison cards that are correct later. The math is unforgiving: Nibbit is 42 to 46 HP on a three-turn loop, Mawler is 72 HP with a 14-damage Tear, and passive ticks at 2 per turn do not clear those bars inside the loop windows. Backstab, the 0-cost burst our entry says fits every Silent deck, and Neutralize, the starter our database calls the strongest starter card in the game at 3 damage plus 1 Weak for free, carry these fights while you set up. A poison deck that tries to be a poison deck in Act 1 dies as a poison deck in Act 1.
Before the Act 1 boss: one Noxious Fumes and one direct applier, with the first Fumes upgrade done if a rest site allowed it. The boss pools on both Act 1 variants reward early engines, the Bygone Effigy sleep window and the Lagavulin Matriarch, which our bestiary notes starts asleep and gets worse the longer the fight runs, are free setup turns, and Fumes ticking through them is the best value in the act. Upgrade discipline follows our mistakes page: upgrading the key card usually outvalues healing, and for this deck the key card is obvious.
Before Act 2, the Infested Prism gate: the 200 HP elite our enemy guide calls the litmus test. Fumes upgraded, an applier beyond Fumes itself, Catalyst found or shoppable, and a thin deck. Thinness matters more here than for any other Silent archetype, because you need engine pieces to meet each other in a 5-card hand; every dead starter is a turn the clock does not run. Removal budgeting under Ascension 6 Inflation, where shop removal starts at 100 gold and climbs by 50 per use per the v0.102 patch notes, should spend on Strikes first: this deck's attacks matter least, since Poison carries the damage, while Defends keep you alive to the kill turn. That is the exact opposite of the Strength build's removal order, and it is the single most common mistake transferring players make.
Events, from our events guide with poison priorities overlaid. Abyssal Baths, soak for 2 Max HP at 3 damage, repeatable, is a strong take; this archetype trades HP comfortably early and Max HP raises the ceiling on every long fight later. Aroma of Chaos transforms a dead card, which is removal with better optics. Self-Help Book empowers your core card, Fumes, always. Byrdonis Nest, eat the egg for Max HP. The removal-versus-upgrade family of events all point the same direction: cut starters, then upgrade the engine.
Campfire ladder, final form: Noxious Fumes, then Catalyst, then Wraith Form, then Backstab. Rate increases on the engine outrank everything, always.
Boss Rhythm: Poison Timing Against Every Act Boss
Act 1a. Vantom opens with 9 Slippery stacks, every hit dealing 1 damage until stripped; the bestiary's counter is cheap multi-hit attacks to burn the stacks off. Poison sidesteps the strip-mini-game entirely: stacks do not attack, so they do not care about Slippery; meanwhile Neutralize-class free chips handle the stacks while the count builds. Full-block turn 3, the 25-plus killer swing, and cash in on the turn 4 self-buff window. The Kin is three bodies, and Fumes taxes all three from turn one; kill acolytes first per the bestiary, and spend direct applications only on the body you chose to delete. The Ceremonial Beast gains 2 Strength every turn and applies Ringing below 150 HP, limiting you to 1 card per turn, so front-load: have the count lethal before the stagger, because Ringing turns gut your ability to apply, though the ticks you already landed keep working every single turn.
Act 1b. The Lagavulin Matriarch, asleep and worsening, is the perfect poison fight: engine up during the nap, count high before it wakes. The Waterfall Giant is the showcase covered in the Wraith Form section, with the one warning worth repeating: the at-0-HP debuff clear wipes your poison, so the explosion turn needs an answer, and Intangible is the answer. Soul Fysh stuffs Beckon statuses, 1-cost, 6 unblockable if unplayed; play them or pitch them, hold Block through the turns 4 and 5 Intangible, and let the count finish.
Act 2. The Kaiser Crab surrounds you, plus 50 percent from behind, and its Rocket claw's 31-damage Laser is the lethal move; Fumes hits both claws from one cast, and your job is to keep their deaths inside a 1-to-2 turn window so the survivor's revenge buff never pays off. The Knowledge Demon, the hardest boss in our database, self-heals and gains permanent Strength while forcing a permanent debuff choice every round, 6 damage per turn or 1 fewer drawn card. Take the damage: draw is your stacking throughput, and decay does not care about your HP total if the count is lethal. The Insatiable is the archetype's nightmare timer: Sandpit starts at 4 and kills you at zero, Escape cards buy turns, and our bestiary says spend everything. Pure passive poison loses to that clock; this is the fight where direct applications and an early Catalyst are not optional, and where attacks like Backstab do real work alongside the ticks.
Act 3. Test Subject C10 is a 600 HP marathon across 100, 200 and 300 HP phases, and our bestiary notes DoTs reset between phases. That single line is your game plan: dose each phase separately, do not over-stack into a transition, and re-cast Fumes-adjacent income if you saved it; phase one punishes Skills, so lead with attacks and Powers. The Queen chains Bound cards that limit your first draws each turn, slams a 99-stack Weak, Vulnerable, Frail turn, and enrages once her Torch Head Amalgam dies; kill the Amalgam first, stack calmly through phase one, then burst, and note her 199 guard layer is exactly the kind of wall ticks work through while attacks bounce. Aeonglass, introduced in v0.105 to replace the Doormaker, reworked in v0.106 and nerfed again in v0.109, rounds out the pool; check its current loop in our Act 3 boss guide before you path into it, because it has changed repeatedly this year.
Snecko Skull and the Rest of the Relic and Potion Board
Snecko Skull first, and there is no second: whenever you apply Poison, apply 1 additional stack. Our relic data lists it as Common, Silent-only, tier A, and calls it mandatory for Poison Silent, which is the correct word. Every Fumes tick rises from 2 to 3 or 3 to 4; every Deadly Poison application gains a stack; every Catalyst doubling multiplies a larger base. It is the single highest leverage pickup in the archetype and it is Common, which means it can appear in any chest or reward; take it over rares without hesitating.
Mercury Hourglass, 3 damage to ALL enemies at the start of your turn, is the parallel clock. It does not stack with Poison multiplicatively, it stacks with Poison in parallel, a second steady income stream that solves the deck's actual weak spot, the early turns before the count is meaningful, and it shortens every normal fight by a turn or two. Red Mask applies 1 Weak to all enemies at combat start, a flat 25 percent off enemy attack damage per our glossary, which is defense this deck gets for free while it stacks. Anchor's 10 starting Block and Gorget's 4 Plating cover exactly the first two turns, when the clock reads zero and the enemy pattern does not.
The boss-relic board leans defensive for the same reason. Pantograph heals 25 at the start of every boss combat, a massive margin-raiser for fights that go long by design. Lizard Tail, revive at half Max HP once per run, covers the archetype most likely to be sitting at single-digit HP when the clock finally wins. Ice Cream conserving energy between turns banks for the Catalyst turn, when you want to apply, apply and double in one turn. Ectoplasm's extra energy with no gold is a fair trade for a deck whose key cards cost 1. Bag of Preparation, draw 2 extra on turn one, raises the odds the engine starts on turn one, which for Fumes is worth more than most rare relics.
The anti-picks are as instructive as the picks. Paper Phrog and the whole Vulnerable package, build-defining on Ironclad, do nothing here: Vulnerable amplifies attack damage only, per our glossary, and Poison is not attack damage. When a Phrog shows up in your rewards, remember you are drafting a different resource game, and pass without guilt. The same logic demotes attack-buffing relics below defense and draw for this deck specifically.
Potions, from our library with timing overlaid. Duplicator on Catalyst is the dream, two doublings back to back, and on Fumes it is a permanent income raise; the potion library's stated use for the bottle could not fit this deck better. Ghost in a Jar is the one-turn Wraith Form, drink it on a blast turn like the Waterfall Giant's detonation. Weak Potion at boss openers before big telegraphs, matching the listed timing. Swift Potion digs for Catalyst on the decisive turn. Liquid Memories returns a card from the discard at 0 cost, and the card you want back is always Catalyst. Fairy in a Bottle is never drunk, only held.
Losing Matchups, Co-op Value and Pivot Lines
Every weakness of this archetype is a version of the same sentence: something interferes with the timeline. The Insatiable's Sandpit hard timer kills you at zero regardless of your count, so pure passive poison can simply run out of game; the answer is direct applications and early doubling, but respect that this is a losing matchup for the passive version. The Knowledge Demon heals itself, raising your effective stack target above its printed 321 HP; add margin or bring a second doubling. Test Subject C10 resets DoTs between phases, so over-stacking into a transition is wasted damage; dose per phase. Artifact fronts are the quiet one: Mecha Knight carries 3 Artifact, which eats applications, poison included, so front-load cheap applications to burn the charges before committing real stacks, or path away, since our bestiary calls it the deadliest elite in the game anyway.
The early game is the other soft spot, covered at the act gates but worth the recap: before the engine exists, this is a fair deck with bad cards, and Nibbit and Mawler punish that. The discipline of drafting real damage first, Backstab and friends, is not a compromise of the build; it is the build.
Co-op is where the archetype gets its reputation, and our build entry says it plainly: great in co-op. The reason is the scaling model in our co-op guide: enemy HP equals base times player count times an act coefficient, 1.1 in Act 1, 1.2 in Acts 2 and 3, 1.3 on the Act 3 boss, so a four-player party faces roughly 4.4 to 5.2 times the HP. Burst decks stall into that wall; a time-based clock does not care how long the fight runs, and co-op fights run long. The community role assignment in our co-op guide names Silent the debuff and poison amplifier: you stack and apply Weak for the whole table, since debuffs like Vulnerable and Weak are shared team-wide, while the Ironclad tanks. Two specific notes from the co-op rules: Mend at campfires heals an ally 30 percent of their Max HP, which covers your fragile mid-game, and keep the tankiest player alive is the iron rule, because your clock only needs time, and time is what a living tank buys.
Pivot lines, because sometimes the cards just do not come. No Noxious Fumes by mid Act 1: the discard core you probably drafted for consistency, Acrobatics-class outlets, points at the Sly Discard build, S tier and covered in its own guide. Attack rewards flooding instead: Blade Dance plus Accuracy-scale Shivs is a real deck with real overlap in your early picks. Everything halfway: an Adrenaline plus Backstab aggro shell with a poison backline, two or three applications and a Catalyst, wins plenty of runs without ever being the pure archetype; our build table's A tier is a floor, not a ceiling, and the consistent clause is the one that matters.