Just beat the penguin level and I'm kind of freaked out because Batman RIPPED SOLOMON GRUNDY"S HEART OUT (literly reached into his chest) and he seemed to have no prior knowledge of Grundy so i don't think he knew he'd come back. This version of Grundy has been sitting in penguins basement chained to a wall since before he bought the iceberg lounge and no one knew him or thought he could be alive due to how old his legend is. it stands to reason Bats never met this version of Grundy and thus dosen't or didn't know about his being immortal. Also whenever i read a comic with batman easdropping on random crimminals theres always somebody who sais "did Batman kill him?" but then someone else is like "haven't you ever gone up against the bat before? he doesn't kill how do you think the boss is still around?" the person who sais he dosen't kill wasn't there this time. Oh and also he seemed willing to let Mr. Freeze kind of ice bleed out if he didn't get info but this was probably a joke. still despite the fact that freeze has fought batman in this universe he seemed like he believed he would let him die.

I don't think that counts because technically Grundy's already dead. He always comes back no matter what.

And the Freeze thing was just for intimidation.