If you got Azazel with that level of ammo, Mephisto should be no problem
The NecroVisioN developers, The Farm 51, are part of the team that made a game called Painkiller. The bosses in that are even more insane than NecroVisioN
. If you enjoyed NVN, you might also enjoy Painkiller. It's 5 years old and so you can find it cheap on Steam or any of the big retailers. However, the graphics and gameplay have stood up well.
Loads of luck with Mephisto.
Cheers