My question is a simple one. Does Hunter's Guile work on the Fire Rune?

Fire Rune:
{Skill} Perform a {ranged attack} rolling 1 red die. Each {hit} of this attack causes the defender to suffer damage equal to {unstable energy} instead of your threat.

Hunter's Guile:
{Melee} {Ranged Attack} If you are at range 1 - {natural energy} of overgrown terrain, you may replace 1 of your dice with a white die.

Could I replace the red die from the Fire Rune with a white die if I have Hunter's Guile and I'm in range of an overgrown terrain?

Sure, why not. They both refer to a ranged attack.

I would think so, yes. And they have built in precise 1. So not a bad combo at all.