Yes. All of the throne rooms are just below the place with the magic nexus in each city. Dekon's is just beneath the canopy(in fact, it is the last room in the trunk before it splits off into smaller branches, and if you look up, you can barely see the magic nexus that powers him. Saala's is just above the voting hall, and is bare of any decoration save windows at regular intervals and three orbs set into the floor in a circle around the center of the room. This is where Saala generates her mouthpiece (which can be any size, BTW, and in fact Saala has found "as tall as the room" to be a conveniently imposing size for the purposes of greeting supplicants and champions). Aqua's is similarly at the top of the central tower (incidentally, this central tower is the one constant of Aquacor's skyline), and her throne is opposite the archway where someone can press open the door. Obsid's throne room is encrusted with the gold, minerals, and jewels he found in life, and the floor is etched with the dragon's image, curled up and expanded to fit the room.
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So naturally, when the floor of Obsid's room rises up to attack the party, they are given fair warning of what their opposition is.