Here is a solid Medivh the Guardian Yogg Priest Deck. I played a few 
games with this deck and it’s really strong, there is loads of synergy to out value opponents, it has the control tools to beat down aggro, and of course you can always Yogg for the random win condition.
Medivh, the Guardian is good in the slower control decks, and Priest is one of the strongest classes for control. I didn’t include any higher mana cost spells than 6 mana because they are not really needed. You’re going to have control of the board and one massive minion isn’t what Priest needs to overwhelm an opponent.