Feats

Boon of Poison Mastery

Prerequisite
Level 19+
Ability Score Increase
+1 to any ability score (max 30)
Source
FRHoF

You gain the following benefits.

Antitoxic

You have Immunity to Poison damage and the Poisoned condition.

Perfect Poisoner

Once per turn, when you roll dice to determine Poison damage a creature takes from your attack, spell, or feature, you can instead use the highest number possible for each die.