Say I control a Trostani Discordant. My opponent casts In Bolas's Clutches on Trostani. At the end of opponent's turn, Trostani triggers and "each player gains control of all creatures they own". Does Trostani return to my control or does the Clutches' effect take precedence?
My guess is that this is a time stamp issue, in which case usually the later spell takes precedence. Therefore Trostani stays under my opponent's control. However Trostani's effect is a trigger, so I am not sure. I'm also unsure if In Bolas's Clutches creates a continuous effect that overrides Trostani's trigger. In particular, In Bolas's Clutches doesn't say "when [this card] enters the battlefield, gain control of ..."; it simply says you control the permanent, which could mean it applies a state-based action to gain control of the permanent if you ever lose control of it.