Dragon Age: Inquisition - Wicked Eyes and Wicked Hearts - Three Way Truce

Though the game doesnt let you know, it is possible to broker peace between all three leaders. You just have to find evidence to blackmail all three. The game notifies you that you can blackmail Briala and Gaspard, but it doesnt let you know that evidence against Celene exists.\r
The evidence against Celene is behind a magic door in the Royal Bedroom Wing of the palace. It requires 5 halla statuettes to be opened, (so do not use the statues to open doors until you have evidence against Celene). Make sure to get this evidence before pursuing evidence against Gaspard. Finding the dirt on Gaspard (and the truth about his sister) is a point of no return.