Paralox

Any time a creature dosn't untap at its controler
untap step, put a -1/-1 counter on it.
If a creature would be destroyed as a result of one
of this counters being added, add as many +1/+1 counters to the Paralox as -1/-1 counters the destroyed creature had acumulated.
{t}: Tap target creature you don't control.
It dosn't untap at its controler untap step.