That said, I'm completely unqualified to build my own sideboard because I have only a hint of my own weaknesses and almost no knowledge of current decks other than my own. For now, my sideboard is a kind of first aid kit. I don't know what kind of injury I'm likely to sustain, but I've assembled the most likely remedies based on what other people do in emergencies.
I'm building my initial sideboard by using a deck database, looking up vampire decks that win tournaments. I looked at all their sideboards, and ranked cards by popularity. This provided me a blind list of what might be helpful, kind of like throwing together a bunch of different sized bandages in hopes your injury will be applicable. Some of the cards were already in my main deck (a potential warning sign). Here's what I came up with:
Popular Vampire Deck Sideboard Cards (in order of popularity)
- Mind Sludge
- Sadistic Sacrament
- Malakar Bloodwitch
- Marsh Casualties
See Learn How To Sideboard, Dammit! for sideboard advice (and some abuse).
Deathmark appears to be the most popular vampire deck sideboard card.
Cheap. Targeted. Useful 40% of the time.