I have a solution, or at least, part of a solution. Make it so the super can’t deal damage through walls. As a warlock main, I can confirm it is absurd.
Edit: First of all, I do not think nova warp is the only broken super in d2 (titan hammers basically make titan’s other roaming supers irrelevant in pvp, blade barrage is a direct upgrade to nova bomb, etc). Secondly, other supers can kill through walls? Wow, I guess this wasn’t as big an issue as I thought.