Conductivity. I really want to like this feat, it seems very cool, but I think unless you made multiple characters in mind for one to have it, it'd never get used. When hit by an electrical attack, you can shoot an arc of lightning for half the damage you just took at any target within 30 feet. I can see a couple ways a party could use it, or maybe some hijinks if you get it on an advanced shocker lizard familiar, depending on how you interpret the feat's damage to work with a electrical-immune creature. But most of the time, it just won't be useful.