Text (SC): 1/1. ; {2}{B}{B}: Target creature gets -1/-1 until end of turn. Put a +1/+1 counter on ~this~.
If the target creature is not a legal target when the ability resolves, then this creature does not get a counter. [Scourge FAQ 2003/05/30]
If it targets itself, it gets both -1/-1 and the +1/+1 counter during resolution. Since state-based effects (like being at zero toughness) are not checked until resolution is done, it does not die. [Scourge FAQ 2003/05/30]
