No, a turn is the movement and the action of one player plus additionals given to him by cards.
A round consists of the turns of all players including the Evil Wizard player.
But it doesn't matter for this card cause I just now read the introductory sentence that the card is to be played at the end of the EWP's turn, which clarifies things to the point that the next round will be including the full next EWP's turn. Sorry. Once again, I posted faster than I thought.
"Until the beginning/end of your next turn" is what I use as a template for duration effects in my rule writing which serves the larger than life purpose of making HQ rules uninterpretable. No need for you to be as picky as me, then.
