Nidhoggr, Root Gnawer

Deathtouch, devour 1 (As this enters the
battlefield, you may sacrifice any number of creatures.
This creature enters the battlefield with that many
+1/+1 counters on it.)
Whenever Nidhoggr, Root Gnawer is goaded,
put a -1/-1 counter on it.
"I there saw wading through rivers wild treacherous
men and murderers too, [...]There Nithhogg sucked
the blood of the slain," - Poetic Edda