woo//ponderous conclusion
@thefishcrow
I can't speak to much knowledge of druidic systems.
That said, if I were trying to work a fire-association into a land-sea-sky metaphor, I'd personally look to either lava / magma / volcanos as part of the 'land' component, or the sun as a 'sky' component.
If the system is not strictly limited to three symbols, then maybe throw a 'cosmos' in there with solar / fire aspects .
Apologies if I'm speaking out my ass here. :)