(Each in the mana costs of permanents you controls counts toward your devotion to black.) Your opponents can't gain life
Their effects are limited, and they only feature certain types of spells
This templating can be explosive for vehicle decks, as you can have all your vehicles chain-crew one another before the first combat, then have Anzrag untap ALL of them for a huge second swing
If you can put some poison counter-generating cards like Infectious Inquiry and Ichor Rats into your deck, Yawgmoth can proliferate those as well, though this does risk making you public enemy number one at your table
Why would you play Rajah Ghostly Tiger when Madam Mim Snake exists, and its only a handful of cents more
In most matchups, you will bring in some combination of cards to prepare against their hate cards unless they have nothing, and against fair decks youll usually sideboard in Show and Tell as an alternate game plan