Not enough stock
event is always available, inexpensive, and offers you some choice in the types of cards you get, plus it adds far more total cards to your collection than a booster
Take a look at my Draft deck from Grand Prix Madison: 2-1 the first pod
Living weapon means that Kaldra Compleat will spawn a 0/0 Black Phyrexian Germ token on play and equip itself to that token and because of haste, that token will be ready to fight as soon as Compleat hits the board
Triton Shorestalker, Slither Blade, and Mist-Cloaked Herald are just a few, with Shoreline Looter being the best unblockable creature as it'll give you card draw as well
Its color identity also helps, since you can return this creature itself via other means without that counter to do it again, or remove the counters with other cards in Black