This developer video talks about the Siren, one of Bioshock Infinite's "heavy hitter" enemies. The Siren, a homage to a turn-of-the-century fascination with the occult, sings a song that revives enemies you've already killed.
Squaring off with the Siren presents a perplexing problem: Taking her down will defeat all the other enemies she's revived: Do you risk getting shot by a whole bunch of enemies to take the Siren down first? Or do you defend yourself from the revived attackers, waiting for an opportunity?
You'll have to make that decision for yourself when Bioshock Infinite hits stores October 16th.