Current Storage (4e Feat)
From D&D Wiki
Your body is capable of storing small amounts of electricity, allowing you to take less damage from shocks and invigorating you when the shocks are minor enough.
Prerequisite: 11th Level, Con 13
Benefit: You gain Resist Lightning 5. If you are hit by an attack with the lightning keyword, you gain temporary hit points equal to one-half your level plus your Constitution modifier.