Youre mostly countering spells on your opponents turns anyways, and in a multiplayer formats, youve got several turns that arent yours where you could use Force of Negation
Speaking of proliferate: Glistening Sphere, Contagion Engine, Yawgmoth, Thran Physician are all great pickups in the deck
This makes Glissa, Herald of Perfection far stronger than it looks, beyond the scope of just the March of the Machine set
Razaketh is an evasive threat with both flying and trample, but its power lies in its activated ability that allows you to pay two life and sacrifice a creature to tutor for any card in your deck at instant speed
it reads When this Equipment enters, create a 1/1 colorless Hero creature token, then attach this to it
Another way to get a little extra ramp in mono black, Scrounge for Eternity is pretty efficiently costed if your curve remains lower like in a Clerics deck, for instance