Nakarkos

Ward—Mill until you mill a creature card.

Ossify (If this creature isn't Ossified, you may pay {1} any
number of times. For each time, mill or discard a card.
Put X +1/+1 counters on this creature where X is the
number of creature cards moved this way for as long as it's
Ossified. It becomes Ossified. Activate only as a sorcery.)

{x}{u/b}, {t}, Remove X +1/+1 counters from Nakarkos,
Exile X creature cards from a graveyard. Target player
mills X cards. Nakarkos is no longer Ossified.