Kheru Bloodsucker
{2}{B}
Creature -- Vampire
2/2
Whenever a creature you control with toughness 4 or greater dies, each opponent loses 2 life and you gain 2 life.
{2}{B}, Sacrifice another creature: Put a +1/+1 counter on ~this~.
Sultai Flayer
{3}{G}
Creature -- Snake Shaman
3/4
Whenever a creature you control with toughness 4 or greater dies, you gain 4 life.
Ulvenwald Observer
{4}{G}{G}
Creature -- Treefolk
6/6
Whenever a creature you control with toughness 4 or greater dies, draw a card.