Yuri, Dream Geist

Indestructible
When Yuri, Dream Geist enters the battlefield
choose a creature type.
Multicolored creatures you cast of the chosen
type cost {w/u}{w/b}{b/r}{b/g} to cast.
As long as you control eight or more humans,
creatures your oponents cast cost {w/u}{w/b}{b/r}{b/g}
more to cast.