Erella, Lone Cathar

Notorious 3 (When this creature attacks the player with the least life or tied for least life, if it is not notorious, put 3 +1/+1 counters on it and it becomes notorious.)
As long as Erella, Lone Cathar is notorious, it can only attack the player with the least amount of life. (If two players are tied for the least amount of life, Erella can't attack.)