Spectral Guardian is a little weird here, but it protects our Vehicles from point removal while they're not Creatures - it's kind of a corner case, but it's worth knowing about
Sefris really shines in a graveyard-centric build but would still do well in other archetypes
Forum Necroscribe Graveshifter Grim Reaper, Lethal Legionnaire Grub, Storied Matriarch Hazel's Nocturne Hex of Undeath Illicit Masquerade It Doesn't Add Up Live or Die Macabre Reconstruction Macabre Waltz Moseo, Vein's New Dean Mourner's Surprise Nullpriest of Oblivion Prison Break Pull from the Grave Queen's Bay Paladin Ral Zarek, Guest Lecturer Rat King, Verminister Sanguine Indulgence Scavenger's Talent Scrounge for Eternity Sidisi, Regent of the Mire Soulcoil Viper The Soul Stone The Terminus of Return Unbury Unliving Legionnaire Valgavoth's Faithful Vampire Soulcaller Viggo, Enforcer of Ig's Crossing Visage of Dread Wail of War Xu-Ifit, Osteoharmonist Zombify Zuko's Conviction
While some provide powerful effects from the get-go, others might need some time before they can unleash devastation on your opponent
Given that you needed at least four permanent types just to transform into this, that means you should be getting at least four mana per tap - and thats only going to become more as the game goes on
Serena is also a useful card in the current format, serving as either a last-ditch draw Supporter or additional copies of Bosss Orders if needed