Thanks for the in depth analysis on Serenitrove!
For the purple section, those blocks are Obsidian, which have a hardness of 30. That means you'll need at least 30 combined stamina and Power to dig through them. The yellow stop sign indicates that while your stamina isn't zero, it's not enough to break through that specific block.
Full Burn immunity without any tradeoffs felt a bit too overpowered, since it would remove much of the challenge from the Magma zone. So the design currently offers a choice, Magmawalker grant directional Burn protection, while Winterheart provides full immunity but comes with a -1 Power penalty (though a high Power stat can offset that).
For Nix runs that made it to the water, players have generally prioritized maxing Power upgrades in Dojo (with +1 Power from Relics), starting with the Sanguine Signet, collecting every Quartz and gem along the way, and then swapping to Winterheart in the Magma zone with shield stacks up. Afterward, they usually switch to a different accessory when shield breaks, since the -1 Power from Winterheart becomes equivalent to taking 1 Burn damage per dig anyway.
Totally agree that Gilded Shift is in an awkward spot right now. It ends up feeling redundant once stronger accessories are available and stamina tradeoffs become less important. I'm still thinking through ways to tweak it so it becomes more relevant without becoming overpowered.
