Poison Swamp is an Ultimate Weapon that creates a damaging zone on the battlefield. Enemies caught in it take damage every second for as long as the swamp stays active, and anything it hurts keeps a Poisoned tag until it dies. Poisoned enemies move 25% slower while standing in a swamp and interact with the Harmony Conductor mod if you have it equipped.
The damage shown in-game accounts for your crit and super crit factor and chance. One undocumented behaviour worth knowing: each tick of swamp damage ramps up. The second tick applies the listed ramp bonus (50% at base), and every tick after that grows by that bonus plus 100%. So a swamp dealing 100x damage with base ramping ticks for 100x, 150x, 300x, 450x, 600x and so on.
Verified data
Stone costs taken from our decoded save data, not from the wiki.
| Sub-stat | Max level | Total stones |
|---|---|---|
| Damage | 30 | 13,686 |
| Duration | 14 | 3,500 |
| Cooldown | 15 | 2,010 |
| Fully maxed | 19,196 |
Description
Poison Swamp spawns a zone that damages enemies every second for its duration, with the damage figure factoring in your crit and super crit stats. Anything damaged by it gains the Poisoned tag until death, which slows the enemy by 25% while it stands in a swamp and makes it eligible for Harmony Conductor mod effects.
Although never listed in release notes, Poison Swamp's damage ramps each tick, matching the old PS+0 behaviour. The second tick gains the documented ramp value (50% at base), and later ticks grow by that value plus 100%. A 100x swamp at base ramping therefore ticks 100x, 150x, 300x, 450x, 600x and so on.
Workshop — Basic Upgrades
Once you unlock Poison Swamp, its basic upgrades appear in the Ultimate Weapon menu alongside every other Ultimate Weapon. You can spend stones on Damage, Duration and Cooldown. Damage has 30 levels, Duration has 14 and Cooldown has 15, with a combined stone cost of 19196 across all three tracks (see the cost table below).
Enemies standing where two swamps overlap only take damage from one of them, so stacking swamps on the same spot does not multiply your damage.
| Damage | Stones (Damage) | Duration | Stones (Duration) | Cooldown | Stones (Cooldown) |
|---|---|---|---|---|---|
| 10.00x | 0 | 30s | 0 | 125s | 0 |
| 11.00x | 5 | 35s | 10 | 120s | 8 |
| 13.00x | 11 | 40s | 20 | 115s | 26 |
| 16.00x | 17 | 45s | 35 | 110s | 44 |
| 20.00x | 23 | 50s | 55 | 105s | 62 |
| 26.00x | 29 | 55s | 100 | 100s | 80 |
| 34.00x | 35 | 60s | 120 | 95s | 98 |
| 43.00x | 41 | 65s | 150 | 90s | 116 |
| 55.00x | 47 | 70s | 200 | 85s | 134 |
| 69.00x | 53 | 75s | 260 | 80s | 152 |
Workshop — Ultimate Weapon Plus
Ultimate Weapon Plus abilities become available only after you have purchased all nine Ultimate Weapons. Poison Swamp's plus ability is Death Creep, which adds damage to each Poison Swamp tick equal to a percentage of Poison Swamp's damage. The per-level values are listed in the table below.
| UW+ Cost Table | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Level | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| Cost | Unlocked | 300 | 375 | 475 | 600 | 725 | 925 | 1150 | 1450 | 1800 | 2200 | 2650 | 3150 | 3700 | 4300 |
| Value | 120% | 190% | 260% | 330% | 400% | 470% | 540% | 610% | 680% | 750% | 820% | 890% | 960% | 1030% | 1110% |
Labs — Swamp Radius
Swamp Radius increases the size of your Poison Swamp, letting it cover more ground and catch more enemies at once. The lab has 30 levels; per-level values are in the table below.
| Level | Time | Cost | Value |
|---|---|---|---|
| 1 | 0d 19h 59m | 250,000 | 0.04 |
| 2 | 0d 23h 21m | 285,000 | 0.08 |
| 3 | 1d 2h 53m | 496,980 | 0.12 |
| 4 | 1d 6h 54m | 1,450,000 | 0.16 |
| 5 | 1d 11h 49m | 4,230,000 | 0.2 |
| 6 | 1d 18h 6m | 10,500,000 | 0.24 |
| 7 | 2d 2h 17m | 22,580,000 | 0.28 |
| 8 | 2d 12h 58m | 43,470,000 | 0.32 |
| 9 | 3d 2h 49m | 76,880,000 | 0.36 |
| 10 | 3d 20h 31m | 127,310,000 | 0.4 |
Labs — Poison Swamp Stun
Poison Swamp Stun gives enemies a chance to be stunned when they enter a Poison Swamp. An enemy can only be stunned once per entry, but re-entering a swamp or walking into a different one gives it another chance to be stunned.
The lab has a single level and starts at a 5% stun chance lasting 1 second. Completing it unlocks the Swamp Stun Chance and Swamp Stun Time labs.
| Level | Time | Cost | Value |
|---|---|---|---|
| 1 | 0d 19h 59m | 700,000 | Unlocked |
Labs — Swamp Stun Chance
Available after completing Poison Swamp Stun, this lab raises the chance that enemies are stunned when entering a Poison Swamp. It has 30 levels, with per-level values shown in the table below.
| Level | Time | Cost | Value |
|---|---|---|---|
| 1 | 0d 19h 59m | 250,000 | 7.5% |
| 2 | 0d 23h 21m | 285,000 | 10.0% |
| 3 | 1d 2h 53m | 496,980 | 12.5% |
| 4 | 1d 6h 54m | 1,450,000 | 15.0% |
| 5 | 1d 11h 49m | 4,230,000 | 17.5% |
| 6 | 1d 18h 6m | 10,500,000 | 20.0% |
| 7 | 2d 2h 17m | 22,580,000 | 22.5% |
| 8 | 2d 12h 58m | 43,470,000 | 25.0% |
| 9 | 3d 2h 49m | 76,880,000 | 27.5% |
| 10 | 3d 20h 31m | 127,310,000 | 30.0% |
Labs — Swamp Stun Time
Available after completing Poison Swamp Stun, this lab extends how long enemies stay stunned by Poison Swamp. It has 30 levels, with per-level values shown in the table below.
| Level | Time | Cost | Value |
|---|---|---|---|
| 1 | 0d 19h 59m | 250,000 | 1.3 |
| 2 | 0d 23h 21m | 285,000 | 1.6 |
| 3 | 1d 2h 53m | 496,980 | 1.9 |
| 4 | 1d 6h 54m | 1,450,000 | 2.2 |
| 5 | 1d 11h 49m | 4,230,000 | 2.5 |
| 6 | 1d 18h 6m | 10,500,000 | 2.8 |
| 7 | 2d 2h 17m | 22,580,000 | 3.1 |
| 8 | 2d 12h 58m | 43,470,000 | 3.4 |
| 9 | 3d 2h 49m | 76,880,000 | 3.7 |
| 10 | 3d 20h 31m | 127,310,000 | 4 |
Labs — Swamp Rend - Basic Enemies
Unlocked in Milestones at tier 16 wave 50. When a basic enemy is hurt by Poison Swamp, the damage is increased by a percentage of the rend currently applied to it. The lab has 30 levels, each adding 3% of rend for a maximum of 90%.
By default this only works on basic enemies; you can extend it to other enemy types through the Swamp Rend - Additional Enemies lab.
| Level | Time | Cost | Value |
|---|---|---|---|
| 1 | 8d 8h 0m | 100.00B | 3% |
| 2 | 9d 7h 59m | 150.00B | 6% |
| 3 | 10d 10h 52m | 225.00B | 9% |
| 4 | 11d 16h 59m | 337.50B | 12% |
| 5 | 13d 2h 42m | 506.25B | 15% |
| 6 | 14d 16h 28m | 759.38B | 18% |
| 7 | 16d 10h 45m | 1.14T | 21% |
| 8 | 18d 10h 8m | 1.71T | 24% |
| 9 | 20d 15h 11m | 2.56T | 27% |
| 10 | 23d 2h 36m | 3.84T | 30% |
Labs — Swamp Rend - Additional Enemies
Unlocked in Milestones at tier 16 wave 50, this lab lets Swamp Rend affect enemy types beyond basics. Affected enemies get the same rend percentage as basic enemies do. The lab has 6 levels.
| Level | Time | Cost | Value |
|---|---|---|---|
| 1 | 8d 7h 59m | 100.00B | Ranged enemies |
| 2 | 9d 8h 0m | 150.00B | Fast enemies |
| 3 | 10d 10h 52m | 225.00B | Tank Enemies |
| 4 | 11d 16h 59m | 337.50B | Protector Enemies |
| 5 | 13d 2h 42m | 506.25B | Boss Enemies |
| 6 | 14d 16h 28m | 759.38B | Vampire |
Labs
Poison Swamp's labs are unlocked in Milestones at tier 7 wave 50, which opens up Swamp Radius and Poison Swamp Stun.