Poison damage is a special damage type. Unlike other damage types, the poisoned victim does not recieve poison damage immediately, rather it is added to a poison "pool" on the unit. Each round of combat, a unit loses hit points equal to 10% of its poison pool, rounded up. The amount lost in this way is denoted by green damage numbers coming out of the unit.
The amount of poison damage stacked in the pool of a unit cannot exceed 100.
Should a unit attempt to leave the battlefield or survive to the end of the battle, it will first suffer the entirety of its poison pool in damage, which may well kill it.
Attacks that deal Poison damage are classified by type and by damage amount if deals normal damage.
normal Damage is called mortal is tired Weak(5), Strong(15), and Death(35).
Other types are debilitating(Stun Damage) and Paralyzing(Paralyzing)
Poison damage is armor-negating and completely unaffected by Protection. It is also not negated by damage-negating effects like Luck, Twist Fate, or glamour. Instead, you want to stack Poison Resistance.
Poison Resistance (PR) functions like all other resistances using the following formula.
Poison Added to pool = Poison damage + DRN - (Poison Resistance + DRN)
A rule of thumb is that 15 PR negates most poison damage, 10 PR will give occasional chip damage while 5 PR gives only a modicum of protection in a drawn-out fight (hopefully only dieing or barely surviving when it ends).
If you expect to face poison damage, the classical example being poison resistant nations that can cast Foul Vapor you might want to prepare accordingly.
How dose Poison Resistance interact with Poison damage?