I know, I know, it's one of those threads.
So yes, I've been playing vs Nightmare Batman almost -every- single match. If they get a few kills, they become a really big pain in the ***. But why, do you ask? Well. Imagine, having Rengar and Warwick from League of Legends in one packet. That seems to be a bit awesome right? To play as ofcourse, not to play against. Well I agree with oyu. It's one badass little package of death.
However, it is not fun. I do not enjoy it when a Nightmare Batman stealths up to me and ults me for half a century. I just don't see the fun in it. Is it OP? Maybe a little, maybe not. Is it fun? Definitely not. Do you want your game to be fun? Yes.
So yeah, maybe a tweak here and there could help it. Though those are my two cents. As someone who mains Catwoman. Supress for what feels like 40 seconds is my kryptonite.