Old Royal Decree targets:
Actions you are about to never want to use again:
Sea Hag, Witch, Lookout, Trading Post, Forge, Duchess, Ruins, Necropolis, Secret Chamber, Marauder, Cultist, Rats, Swindler?, One-shots like Feast (Island might work?)
Actions that like getting trashed, especially when you don't have the opportunity to play them:
Cultist, Rats, Fortress, Squire, Catacombs, Hunting Grounds, Sir Vander, Anything that could be a Rogue or Gravedigger target latter in the turn.
Extremely late game situations when having an action for the next reshuffle is less important.
Regular Late game when you need certain actions to line up, especially if some of them are terminal.