Mÿri, Coven Usurper

Swampwalk (This creature cannot be blocked as long
as the defending player controls a Swamp)

Whenever a green creature enters the battlefield under your control, Mÿri gains your choice of a +1/+1 counter or Lifelink until end of
turn

Whenever a black creature you control dies, Mÿri gains your choice of a +1/+1 counter or Deathtouch until end of turn