Ob Nixilis' Hedron Nexus

At the begining of your upkeep sacrifice a creature or Ob Nixilis' Hedron Nexus deals damage to you equal to the number of lands you control
Black creatures you control get +1/+1
Demons you control get +1/+1
Swamps you control are indestructible
The Center of a demons power is never hidden, only well guarded.