With the anomaly Cosmic Duality, I got Power of the Storm as Marin the Manager (My Trinket was Naga Compass). I chose King of Elementals once and couldn’t swap off A Tale of Kings. All Power of the Storm showed me was a different A Tale of Kings Tribe variant each turn. https://i.postimg.cc/1zV9Gh6P/image.png
I had the same just now. As Marin the Manager with Cosmic Duality, if you get once the Rat King’s hero power, the game locks it in, and offers the choice each turn, to choose from only 1 option. (What you would already get with said Rat King’s hero power)
I also just came to report this, also using Marin. On Turn 5 I selected Great Boar Sticker as my Trinket. Then for Power of the Storm, the only option I was given was A Tale of Kings (Elemental). On subsequent turns, Power of the Storm would refresh and either offer nothing, or offer only A Tale of Kings.