Here is the situation:
I attack with a Halo Hunter (Black demon creature with intimidate)
Other player blocks with Blood Seeker (Black Creature, so legal to block)
Now can I play Illusion/Reality on the Blood Seeker ("Target spell or permanent becomes the color of your choice until end of turn.") and change its color to a different color (lets say, white?) What will happen will my Halo Hunter become unblocked or what?