Heroes of the Storm has become my go-to game for about two years now. Very fun MOBA that appeals to my Diablo lore as well as many other countless Blizzard characters. Ironically, Marvel Heroes, later rebranded to Marvel Heroes 2015, 2016 and Omega, would've been the clear cut winner and answer to the original poster's question. David Brevik made it a lot like Diablo II but with a ton of Marvel superheroes and team-up heroes. It was such an awesome and addicting game! In fact, I'd have even considered it slightly better than D2 which is saying a lot! I've played Diablo II classic since its initial release in June of 2000.
But Gazillion, the company that owned Marvel Heroes and paid for the licensing rights from Disney-Marvel. shut down in November of 2017 because of poor leadership after Mr. Brevik had left in early 2016. So we lost an amazing gem of a game. For about a year after Marvel Heroes Omega shut down and before finding Heroes of the Storm, I also played Drakensang Online which is also a fun game. It kind of has a Diablo II feel to it but it's more of an open world and MMORPG with mounts and stuff like that. I may try and get back into it Drakensang Online one day but Heroes of the Storm is enough to satisfy me for now.
I'm kind of waiting for Diablo IV but I don't have high hopes anymore. I'm getting older and I need to game right now! I can't wait forever...