I looked up how the Shifting Core accessory works. Before I start, here's what Tower had to say about it when it was put in the game.
But! The flag the core sets is also used by the Chunga Root and Torquoise Piercing, and will overwrite the old resistance if it's there. So if you used the Piercing to get a swimming progeny, then don't equip them with the core.
Whenever a progeny equipped with the core takes Hot, Cold, or Poison environmental damage, there's a 2% chance for the progeny to gain resistance to that element. This consumes the core.I love the Black Cat Jar and the Shifting Core deeply, so I've made them difficult to get (the Jar) and difficult to understand (the Core)!
This is what I get off to
But! The flag the core sets is also used by the Chunga Root and Torquoise Piercing, and will overwrite the old resistance if it's there. So if you used the Piercing to get a swimming progeny, then don't equip them with the core.