Trundle's W is "If you fight me in this area, I will win, but if you can pull me off of it, it'll be a much closer fight." Trundle also has the ability to keep you in the area with his E. It's some nice subtle kit synergy.
Nocturne's Q is basically, "I'm rewarded for hitting you, and I'm really good at hunting you down and killing you if I do." He also has this sort of "unstoppable assailant" vibe. He spell shields a CC and if he can stick to you, fears you as well.
There are definitely some interesting things you can do with ground effects. One difficulty is making them look and feel cool (which I think Nocturne does well) while not being too spammy (imagine if Trundle W looked like Singed goo or Malzahar's Null Zone)