710. Controlling Another Player's Turn
710.1. Two cards (Mindslaver and Sorin Markov) allow a player's turn to be controlled by another player. This effect applies to the next turn that the affected player actually takes. The entire turn is controlled; the effect doesn't end until the beginning of the next turn.
710.1a Multiple turn-controlling effects that affect the same player overwrite each other. The last one to be created is the one that works.
710.1b If a turn is skipped, any pending turn-controlling effects wait until the player who would be affected actually takes a turn.
710.1c Only the control of the turn changes. All objects are controlled by their normal controllers.
710.2. The player whose turn is being controlled is still the active player.
710.3. If information about an object would be visible to the player whose turn is controlled, it's visible to both that player and the controller of the turn.
Example: The controller of a player's turn can see that player's hand and the identity of any face-down creatures he or she controls.
710.4. The controller of another player's turn makes all choices and decisions that player is allowed to make or is told to make during that turn by the rules or by any objects. This includes choices and decisions about what to play, and choices and decisions called for by spells and abilities.
Example: The controller of the turn decides which spells the active player casts and what those spells target, and makes any required decisions when those spells resolve.
Example: The controller of the turn decides which of the active player's creatures attack, which player or planeswalker each one attacks, what the damage assignment order of the creatures that block them is (if any of the attacking creatures are blocked by multiple creatures), and how those attacking creatures assign their combat damage.
710.4a The controller of another player's turn can use only that player's resources (cards, mana, and so on) to pay costs for that player.
Example: If the controller of the turn decides that the active player will cast a spell with an additional cost of discarding cards, the cards are discarded from the active player's hand.
710.4b The controller of another player's turn can't make choices or decisions for that player that aren't called for by the rules or by any objects. The controller also can't make any choices or decisions for the player that would be called for by the tournament rules.
Example: The player whose turn is being controlled still chooses whether he or she leaves to visit the restroom, trades a card to someone else, takes an intentional draw, or calls a judge about an error or infraction.
710.5. The controller of another player's turn can't make that player concede. A player may concede the game at any time, even if his or her turn is controlled by another player. See rule 104.3a.
710.6. A player who controls another player's turn also continues to make his or her own choices and decisions.
What it boils down to is you get to make all decisions that, that player would make for his or her next turn apart form making them concede as laid out in 710.