Infernal Constitution - Fullfeat

Fiendish blood runs strong in you, unlocking a resilience akin to that possessed by some fiends. You gain the following benefits:

• You have resistance to cold damage and poison damage.
• You have advantage on saving throws against being poisoned.
• When you take damage which reduces temporary hit points you had to 0, any remaining damage from that source is immediately reduced by an amount equal to your Constitution modifier. 

[Part of a project to upgrade Half-feats (those granting lesser abilities/effects alongside a single point of ability score increase) to Fullfeats (foregoing any ability score increase to receive a more fully-balanced ability/effect).]