Markruth, Mycosynth's Blight

Toxic 1, Spherewalk (This creature can't be blocked
as long as defending player controls a Sphere.)
At the beginning of each upkeep create a 0/0
black Phyrexian Germ creature token.
Whenever a creature you control dies you may
pay {1}{p/b}. If you do Markruth, Mycosynth's
Blight gains Toxic 1 until your next end step.