Tiahara, The Shadow Man

Creatures with a Shadowless counter on them
can't block.
{b}{b}, {t}: Put a shadowless counter on target creature, create a creature token that's a copy of
target creature that has a base power of X/X,
where X is the inverse of target creature's power
and toughness and has, This creature can't
attack. (Target creature's power is token's toughness,
and toughness is it's power.)