The Harbinger should, obviously, only be played in mono-blue Merfolk decks, and preferably in control shells that focus on icing out the opponent from doing much of anything rather than overwhelming them with tons of creatures, just like Richard Garfield intended
Vanquisher's Banner, Coat of Arms, and Banner of Kinship are all artifacts that'll boost your Vampires drastically
Its windpipe is only the first to amplify its maddening laughter
What is more, overloading Vandalblast comes with no risk, since this card will not affect the caster's own artifacts
You can't do so later in combat, and creatures put onto the battlefield attacking can't be exerted
Every now and again when I bought collections, I would pull these out of the pile of bulk rares that I picked up at a dime a piece, and throw them into my spec box