Toll Bridge

{t}: Add {c} to your mana pool.
Whenever a creature attacks you or a planeswalker you control, if Toll Bridge is untapped, that creature's controller may pay {2}. If he or she doesn't, sacrifice Toll Bridge and create a 3/3 green Troll creature with "{g}{g}: Regenerate this creature."
"Can't I just solve a riddle or something? " -Elric the Thrifty, last words