zad question

[bebe]

What happends if you play Zad and have less than 7 cards in your library? ... and what if both players have less than 7 cards in thier library?)
Does player with priority lose? Do both lose half their life?

[Jebus]

If you have less than 7, you lose the sub-game.

If both players have less than 7, both players lose the subgame.  Since neither player won the subgame, both lose half their life in the main game.