Dorana, Enshadowed Death

Rival {b}{b}(Choose a creature an opponent controls to be this creature's Rival. That creature must block this creature whenever it attacks.You cannot choose a new Rival for a creature until its current Rival leaves the battlefield.)
Deathtouch
When Dorana, Enshadowed Death's Rival leaves the battlefield, put a +1/+1 counter on Dorana, Enshadowed Death.