Emperor Nero "Character is immune to lone Heroes. Only a rescue attempt of 2 or more Heroes can be successful. Discard all Roman sites in play. Errata/Play As: Evil Character is immune to lone Heroes. Discard all Roman sites in play."
peace only works for a lone hero, so yes, unless Emperor Nero is negated in a toss battle where peace is on a lone hero tossing enhancements, it will be a block because Nero is not negated and says "Only a rescue attempt of 2 or more Heroes can be successful." Nero would die if decreased far enough because toss is regardless of immunity or protection, but if his ability remains active it would be a block against a lone hero..
sorry due to the errata which i didn't even know existed, yes you would make a successful rescue assuming the errata eliminates this portion of his ability which i actually thought was awesome..
