Poison Weakness

Poison Weakness: This is a poison effect that reduces your Fortitude Saving Throw.

(Combat): You are hit by (creature's) poison weakness.

(Combat): Due to past poison attacks, your resistance to poison has been reduced. You have a penalty to fortitude saves and have increased vulnerability to poison typed hit point damage. This effect can stack to result in increased penalties and vulnerability.

(Effects): You receive a penalty from Poison Weakness.

(Effects): --- Penalty Penalty(sic) modifier to Fortitude Saving Throws: -21

Monsters with this effect:
 * Underdark Spiders