Poison Damage acts very slowly. Poison builds up in the target like Fatigue, but decays into HP Damage at a rate of 10% each combat round; nothing prevents this damage/fatigue. The type is chosen upon initial application, and some cause paralysis or stunning.

Stun Poison, instead of delayed damage, increases the target's Fatigue and is applied all at once. ( does size affect it now? A bug made this not the case in 5.)

Poison Resistance only reduces the initial application. Likewise, Poison Vulnerability only adds to the initial application.

A unit can possess only a maximum of 100 Poison at a time, just as they can only possess 200 Fatigue. Unlike with Fatigue, however, the excess Poison is completely wasted.

New to Dominions 6, Poison buildup applies a percent penalty to the subject's Attack Skill and Defence Skill; having just as much Poison as max HP provides a -25% penalty, while having twice as much upgrades that penalty to -50%.

Poison cannot be run away from, nor can it be interrupted by completing the battle early. A unit who leaves the battlefield while poisoned has all of it decay off-screen. Any Poison that lasts past the 25 combat rounds of auto-resolving at the end of a battle also decays off-screen. This is why Assassins often carry a poisoned weapon.