Pub Quiz

At the beginning of your upkeep target opponent
looks at the bottom card of your library and tells
you the cards name. If you can guess they overall
mana cost then you draw two cards or can play
the card without paying its mana cost, if not then
the opponent draws two cards. After one of you
has drawn their cards shuffle it into your library.
If you played the card instead don't bother
shuffling the library.