Ludwig, the Necromsmith

Zombies you play cost {b} less to play.
Whenever a zombie enters the battlefield from
another source under your control, put a
experiment counter on Ludwig.
{1}{b}{u}: Remove X experiment counters from
Ludwig, the Necromsmith. You may put a
creature with X or less total cost from your
graveyard onto the battlefield. That creature is a
zombie in addition to its other types. If its already
a zombie, put a +1/+1 counter on it.