Poison is a negative status effect (Debuff) that the Silent can apply to enemies.
At the beginning of a Poisoned enemy's turn, they lose HP equal to the # of Poison stacks they have. Then the Poison stack decreases by 1.
This damage will go through an enemy's 
Block.
The total possible damage that poison can deal over time can be calculated using the following formula: x*(x+1)/2, where x is the amount of current poison stacks. However, since fights generally do not last long enough for all the poison to expire, much of the calculated damage will never be realized before the fight ends.
Other characters can access Poison cards through the A Note For Yourself event, 
Prismatic Shard, or Foreign Influence (Watcher).
Effects that add Poison[]
Cards:
- Deadly Poison: 5(7)
- Poisoned Stab: 3(4)
- Bouncing Flask: 3 x 3(4)
- Crippling Cloud: 4(7)
- Corpse Explosion: 6(9)
- Noxious Fumes: 2(3) per turn
- Envenom: 1 per unblocked attack
- Catalyst: +1x(+2x) existing Poison.
Potions:
Relics:
Twisted Funnel: 4 at start of combat.- Snecko Skull: +1 whenever Poison is applied.
- The Specimen: Equal to dead enemy's Poison.
Effects that take advantage of Poison[]
- Bane: Attacks a second time if the enemy is Poisoned.
- Catalyst
- Snecko Skull
- The Specimen
Other Interactions[]
- Sadistic Nature: Deals 5(7) damage every time Poison is applied.