Livewire nearly killed Supergirl if I recall correctly, and Superman himself during the shows, so she might be a bit much lol.  That said, I'm in agreement about Firefly, I thought he was supposed to be dropping by?  That'd be enough if you ask me.  Save Mr. Freeze for another day.  Hell, I'd be willing to do Freeze for a fight, I love the man that much.  And not the psychopath we got in Young Justice.  I vastly prefer the man we got from Batman the Animated Series.