Nyx, Puppet Master of Dreams

Depending on what land you used for the
non-colourless cost to summon this creature,
certain ability activates:
-if {u} used; give this creature one +1/+1 counter
for each creature on the battlefield
-if {b} used; give target creature -1/-1 for each
creature on the battlefield
They say dreams are made and changed by a person's imagination, but in reality, it's Nyx at work.