In sorin Markovs last ability you control the players next turn how does this work exactly?
You may do anything that player could legally do on his turn for him.
For example, you basically take his seat. You get his hand, an control his mana, creatures, whatever
Wow ok cool what (if any) are the restrictions?
You can actually look through their sideboard as well.
Only restriction is you cannot make him concede the game.
They actually abolished they "look at sideboard" option unless specifically allowed by an effect like {spawnsire of ulamog}.