Peppermint

{s}{s}{b}: Monstrosity 4 (Put 4 +1/+1 counters on
this, and it becomes monstrous)
As long as Peppermint is monstrous, it's a
Demon Horror with flying and menace.
Whenever Peppermint attacks, if it's monstrous, defending player creates a Coal token (It's a black artifact with "At the beginning of your upkeep, you
lose 1 life" and "{2}, {t}: Sacrifice this artifact").