Kavech, the Flenser

Stealth (This creature enters the battlefield with a
stealth counter on it. As long as it has a stealth
counter on it, it has hexproof. Whenever this creature
deals or is dealt damage, remove all stealth counter
from it.)
At the beginning of your upkeep, you may put a
-1/-1 counter on target creature. If you don't,
target player looses life equal to the amount
of creatures with -1/-1 counters on them.