Neck Shackle

When Neck Shackle enters the battlefield, tap target creature, an opponent controls. It remains tapped for as long as Neck Shackle remains on
the battlefield.
At the beginning of your upkeep, if Neck Shackle is on the battlefield, put an age counter
on this permanent. Then you may pay {1} for
each age counter on it. If you don't, return it to
it's owner's hand.