Tainted Syphon

As an additional cost to cast this spell, pay X life.
Target creature you don't control gets -X/-X until end of turn. Put X +1/+1 counters on target creature you control.
Overload {6}{b}{b}{g}{g} (You may cast this spell for its overload cost. If you do, change its text by replacing all instances of "target" with "each".)