The controlling player can’t make any illegal decisions or illegal choices—that player can’t do anything that the player being controlled couldn’t do. The controlling player can’t make choices or decisions for that player that aren’t called for by the game rules or by any cards, permanents, spells, abilities, and so on. If an effect causes another player to make decisions that the player being controlled would normally make (as Master Warcraft does), that effect takes precedence. In other words, if the player being controlled wouldn’t make a decision, the controlling player can’t make that decision on their behalf.