Chitauri Warcaller

When Chitauri Warcaller enters the battlefield, Amass 2. (Put two +1/+1 counters
on a Zombie Army or Chitauri Army you control. If you don't control both, you may create
a 0 / 0 of the type you are missing first.)
The Chitauri Horde advanced upon Ravnica
in never ending waves.