Kuran, the Shadowkin

Kuran comes into play with X Bolt counters on it
{w/b}{w/b}{w/b}, Remove a Bolt counter; Put a -1/-1 counter on target creature
{t}; Put two Bolt counters on Kuran
Whenever Kuran blocks or is blocked by a creature with a -1/-1 counter on it, Kuran gets +4/+4