mtg mono black commander precon Precons The Wakanda Forever precon might

some cards, like Entomb, put a card directly into your graveyard

Two in particular stand out, the Skyline Despot and the Thunderbreak Regent

Adding 2 mana in a combination of colors enables lots of multicolor cards like Omnath, Locus of All, and Niv-Mizzet Reborn which would be far harder to use otherwise

But its not for every vampire build and thats fine

Mystic Remora [Best Early-Game Draw MTG Commander Staple] Mystic Remora provides explosive early-game card advantage at the cost of one blue mana

Legendary horrors, nightmares, demons, and spirits are a good place to start, followed by anything from Magic sets that take place on planes like Innistrad and Duskmourn