Slark, the Nightcrawler

Whenever Slark, the Nightcrawler deals damage to a creature, put a +1/+1 counter
on him. Put a -1/-1 counter on each creature that was dealt damage by him this turn.
{2}{u}{b}, pay 4 life: Slark, the Nightcrawler
gets +0/+4 and shroud until end of turn.