Bezoar

Bezoar is an item only found in the jungle/underground jungle. It has a 1% chance to be dropped by any type of Hornet (Note: This does not seem to include Moss Hornets, so you will need to acquire one before entering hardmode or visit a non-hardmode world.) and Toxic Sludge. This item grants invulnerability to the equipped player to any Poison debuffs.