I dont know if this is intended but i think there is a bug with mirror and fire ring. The mirror does not mimmic fire ring, i can understand that, i think it would be a little too good. But when the fire ring is up, and the Mirror spawns in, it retains the fire ring, until the fire ring runs out, then cant get it again until it spawns in again when the fire ring is active. Again i dont know if thats intended, but i think its a bug.
Edit: I also just found out it works with all mirrored clones, no matter how many, so though i dont think its game braking, maybe late game it could be abused a lot.
Edit2: I did some testing, spamming fire ring and mirror upgrades, and this COMPLETELY SHREDS BOSSES, it is a little rng on whether you get it correct, but when you have a total of 5 fire rings, you can
1. space further away
2. deal more total damage to bigger enemys
So i think this should get fixed, as much as i love it.