Moonswaddled Armor

Armor (any light armor), rare

This comfortable set of armor grants additional protection and respite when worn at night. You gain a +1 bonus to AC while wearing this armor between dusk and dawn, and when you would normally roll 1 or more Hit Dice to restore hit points when taking a short rest after dusk, you instead use the highest number possible for each Hit Die spent. 

Like warming up by a nice fire at your favorite tavern even when you're in the depths of the Underdark.