The 14th level Circle of Wildfire ability reads:
If the spirit is within 120 feet of you when you are reduced to 0 hit points and thereby fall unconscious, you can cause the spirit to drop to 0 hit points. You then regain half your hit points and immediately rise to your feet.
Does the Druid actually fall unconscious first, or does triggering Blazing Revival prevent that?
If the Druid does fall unconscious first, that means they lose concentration on any active spell, drop anything they were holding, and potentially shift out of wild shape (if they were wild shaping while they had the spirit active)
In our last play session we played it as preventing the druid from actually falling unconscious because that was more fun (and kept a Wall of Thorns in front of an enemy Gate spell that had giants running through it active), but I didn't see any existing discussion about this class feature and thought it was worth discussion. Maybe this is best handled as Rule 0 / DM discretion?