Spirit of the bat

{1}-Posses-Enchant target creature: it
gains blood for blood (Whenever a source an
opponent controls deals damage to you or a card
you control this creature deals damage equal to
half it's power rounded up)it also gains flying,
haste and vigilance and it gains +5/+5
{12}-If this spell is attatched to a creature
unattatch it Spirit of the bat becomes a 10/10
with flying, deathtouch, vigilance and shadow