Most played cards in Vampires:

3 Decks
Gatekeeper of Malakir
11 copies - 3.67 average
Dark Ritual
10 copies - 3.33 average
Vampire Nocturnus
8 copies - 2.67 average
Leyline of the Void
8 copies - 2.67 average
Duress
8 copies - 2.67 average
Engineered Plague
7 copies - 2.33 average
Thoughtseize
7 copies - 2.33 average
Doom Blade
7 copies - 2.33 average
Pithing Needle
6 copies - 2 average
Vampire Nighthawk
6 copies - 2 average
Vampire Hexmage
5 copies - 1.67 average
Relic of Progenitus
5 copies - 1.67 average
Umezawa's Jitte
5 copies - 1.67 average
Malakir Bloodwitch
5 copies - 1.67 average
Deathmark
4 copies - 1.33 average
Unearth
4 copies - 1.33 average
Bloodghast
4 copies - 1.33 average
Vampire Lacerator
4 copies - 1.33 average
Blood Seeker
4 copies - 1.33 average
Child of Night
4 copies - 1.33 average