Im not and nor have I ever been an MTG judge, but Ill use my love and knowledge of the game to best interpret the rules
Here, we see the new companion mechanic combined with an extended-art treatment
The deck starts by playing a number of efficiently costed vampires with strong secondary abilities including drain (Astarion, Defiant Bloodlord, Sanctum Seaker), mass reanimate (Bringer), card draw (Champion of Dusk, Crossway Troublemakers, Dusk Legion Duelist), granting your army lifelink/deathtouch (Crossway Troublemakers), +1/+1 counters (Drana), anthem effects (Edgar), creature tokens (Mavren, Preacher, Sanguine Evangelist), Explore (Amalia), removal (Vona), and many many more
Beyond just being fun, Sire of Seven Deaths is also incredibly powerful, packing a serious punch even when removed