Morvor Blackblade

Skulk, (This creature can't be blocked by creatures
with greater power) Infect (This creature deals
damage to players in the form of poison counters and
creatures in the form of -1/-1 counters)
When you cast Morvor, put x -1/-1 counters
on up to one target creature.
When Morvor enters the battlefield, target
opponent gets x poison counters.
Morvor gets +1/+0 for each poison counter
on your opponent/s.
(Adventurers are creatures)