Forcing our opponents to attack each turn also means they'll be tapped down if we want to swing for lethal
Fevered Suspicion is pretty much a gamble
You have cards that make lots of Vampire tokens (like March of the Canonized, Mavren Fein, Charismatc Conqueror, and Sorin), cards that make Vampires bigger (like Legion Lieutenant, Etchings of the Chosen, and Radiant Destiny), as well as cards to keep your Vampires in play (like Timothar, Kindred Boon, and Dusk Legion Lieutenant)
I cant really give an objective evaluation of how good they are, since the main purpose of Planes is be fun, but we can take a quick look at them: Tezzerets home shard on the plane of Alara, and the most metal place in the multiverse outside of New Phyrexia itself
Whatever her motivations, she mortified her kin when she made a demonic pact