Theoretically interesting but if you have enough creatures in play to deal with EDH level threats, your gameplan is probably already working
One of the tricks R&D uses is to put multiple cards in the same card code slot as a way to say "These cards cannot both go into the set so we're trying them out." This keeps the lead designer from constantly getting comments that the cards are too close
In other trading card news, a rare LeBron James 03-04 signature edition rookie card auctioned for over $185,000 USD recently.
Good job
In any case, Garza Zol, Plague Queen is probably the closest well ever have to a Grixis vampire tribal in EDH
You miss out on one of the Marit Lage cards in a Svella, Ice Shaper deck, but Etali, Primal Conqueror is good enough, right