Nolis, the Drago-Cobra

At the beginning of each of your precombat phases,
flip a coin and roll a 6D. If heads, creatures you
control with even mana costs cant be blocked until
end of turn, if tails, creatures you control with odd
mana costs cant be blocked until end of turn. If your
roll is even, double the power of each creature you
control with an even mana costs entil end of turn,
if your roll is odd, double the power of each creature
you control with an odd mana costs until end of
turn.