Trostani Discordant vs. In Bolas's Clutches
You regain control of the Trostani Discordant. All control change effects are continuous effects, and the effect created by Trostani's triggered ability is newer than the effect created by In Bolas's Clutches, so it &quot;wins&quot; and control returns to you.
The continuous effects rules section has the following rules:


611.1. A continuous effect modifies characteristics of objects, modifies control of objects, or affects players or the rules of the game, for a fixed or indefinite period.

611.2. A continuous effect may be generated by the resolution of a spell or ability.

611.3. A continuous effect may be generated by the static ability of an object.



The interaction of continuous effects rules section describes how to apply multiple effects like this. Specifically, rule 613.6 and its relevant subrules say this:


613.6 Within a layer or sublayer, determining which order effects are applied in is usually done using a timestamp system. An effect with an earlier timestamp is applied before an effect with a later timestamp.

613.6a A continuous effect generated by a static ability has the same timestamp as the object the static ability is on, or the timestamp of the effect that created the ability, whichever is later.

613.6b A continuous effect generated by the resolution of a spell or ability receives a timestamp at the time it’s created.





In Bolas's Clutches has a static ability, so its effect has a timestamp from when it entered the battlefield. Trostani's ability creates a new continuous effect when it resolves, so that's the timestamp that effect has. After In Bolas's Clutches is on the battlefield, the next time Trostani's ability resolves, it has a newer timestamp, so it applies last and the overall effect is that you control Trostani.