Tattered Rider

{t}, Put a -1/-1 counter on target creature you don't control, then draw 1 card and gain 1 life for every -1/-1 counter on that creature. Activate this ability only on your turn and once per turn.
{ut}, Remove all -1/-1 counters from target creature you don't control, that creature's controller takes {x} damage and discards {x} cards, where {x} is the amount of -1/-1 counters removed this way.