Roux, the Waking Dream

Creatures get -1/-0 for each mist counter on
them. Each of those creatures you control
assigns combat damage equal to its toughness
rather than its power.
{u}{u}, {t}: Put a mist counter on target creature
you don't control that attacked or blocked this
turn. Its controller gains 1 life and draws a card.
Then if its power is 0 or less, gain control of it
for as long as it has a mist counter on it.