Vicik, Shade Maker

Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)
At the beginning of each player's upkeep, that player may put a -1/-1 counter on a creature they control.
Creatures with one or more -1/-1 counters on them have shadow (They can block or be blocked by only creatures with shadow.)