Endure (4e Feat)
From D&D Wiki
All poison, acid, disease and nature type damage taken is reduced while you are Bloodied, in addition to gaining a +2 bonus to saving throws against such effects.
Benefit: When you are Bloodied, you gain 2 + your Constitution modifier + one-half your level in damage reduction from sources such as poison, acid, disease and nature. This effect lasts until you are no longer Bloodied. In addition, while Bloodied your saving throws against such effects are increased by +2.