I LOVE your use of the stacking theme! If this ever reaches printing, I reeeeeally wanna see the pyramid step and cap be slightly smaller in size so they make actual pyramids on the board!
I also really love the cursing of other players, but I think it can lead to a few questions when interacting with certain factions. For example, if the birds ONLY have two curse cards in hand and HAVE to place a card in the decree, do they end up placing a curse in the decree that does nothing? Or do they forgo that step, or even draw an extra card as part of that little comeback mechanic they have? Just a thought, and I'm sure you have considered it!
Overall really like the thematics and think it would add a pretty villainous role to the faction when you sit down and play!