Ensnaring Bondage

Whenever a creature enters play, attacks or
activates an ability you may pay {b/g}. If you do, tap
that creature and it does not untap during its controller's next untap step. At any time its controller may pay {3} to untap it.
"So nice to finally have some quality time together,
don't you think?"
—Mi'tha'l Von, Proctor VI